2
A linear equation is given in the form ax + by + c = 0, where a ≠0, b ≠0, and c = 0. Through which point does this straight line pass?
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Solution: Step 1: The general form of a linear equation is ax + by + c = 0.
Step 2: Given that c = 0, and a ≠0, b ≠0.
Step 3: Substitute c = 0 into the equation: ax + by + 0 = 0, which simplifies to ax + by = 0.
Step 4: To find a point that lies on this line, we can test values. Consider the point (0, 0).
Step 5: Substitute x = 0 and y = 0 into the equation ax + by = 0:
a(0) + b(0) = 0
0 + 0 = 0
0 = 0.
Step 6: Since (0, 0) satisfies the equation, the straight line passes through the origin (0, 0).
5
Calculate the area (in square units) of the triangle formed by the graphs of the equations x = 4, y = 3, and 3x + 4y = 12.
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Solution: Step 1: Identify the three lines: L1: x = 4, L2: y = 3, L3: 3x + 4y = 12.
Step 2: Find the intersection points of these lines to determine the vertices of the triangle.
- Intersection of L1 (x=4) and L2 (y=3): Vertex P1 = (4, 3).
- Intersection of L1 (x=4) and L3 (3x + 4y = 12): Substitute x=4 into 3x+4y=12 ⇒ 3(4) + 4y = 12 ⇒ 12 + 4y = 12 ⇒ 4y = 0 ⇒ y = 0. Vertex P2 = (4, 0).
- Intersection of L2 (y=3) and L3 (3x + 4y = 12): Substitute y=3 into 3x+4y=12 ⇒ 3x + 4(3) = 12 ⇒ 3x + 12 = 12 ⇒ 3x = 0 ⇒ x = 0. Vertex P3 = (0, 3).
Step 3: The vertices of the triangle are (4,3), (4,0), and (0,3).
Step 4: Observe that the line x=4 is perpendicular to the line y=3. Therefore, the triangle is a right-angled triangle with the right angle at (4,3).
Step 5: The length of the side from (4,0) to (4,3) along the line x=4 is |3 - 0| = 3 units. This can be taken as the base.
Step 6: The length of the side from (0,3) to (4,3) along the line y=3 is |4 - 0| = 4 units. This can be taken as the height.
Step 7: Calculate the area of the right-angled triangle using the formula (1/2) * base * height = (1/2) * 3 * 4 = 6 square units.
6
Calculate the area of the triangle with vertices A(0, 8), O(0, 0), and B(5, 0).
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Solution: Step 1: The given vertices are A(0, 8), O(0, 0), and B(5, 0).
Step 2: Observe that vertex O is the origin. Vertex A is on the y-axis (since its x-coordinate is 0), and vertex B is on the x-axis (since its y-coordinate is 0).
Step 3: This forms a right-angled triangle with the base along the x-axis and height along the y-axis.
Step 4: The length of the base (OB) = |5 - 0| = 5 units.
Step 5: The height (OA) = |8 - 0| = 8 units.
Step 6: Use the formula for the area of a triangle: Area = (1/2) * base * height.
Area = (1/2) * 5 * 8.
Area = (1/2) * 40.
Area = 20 square units.
7
Calculate the area (in square units) of the triangular region bounded by the lines 2x + 5y = 12, x + y = 3, and the x-axis.
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Solution: Step 1: Find the intersection points of the lines with the x-axis (where y = 0).
- For 2x + 5y = 12: Set y = 0 => 2x = 12 => x = 6. Point is (6, 0).
- For x + y = 3: Set y = 0 => x = 3. Point is (3, 0).
Step 2: Find the intersection point of the two lines 2x + 5y = 12 and x + y = 3.
- Multiply the second equation by 2: 2(x + y) = 2(3) => 2x + 2y = 6.
- Subtract this new equation from the first equation: (2x + 5y = 12) - (2x + 2y = 6) => 3y = 6 => y = 2.
- Substitute y = 2 into x + y = 3: x + 2 = 3 => x = 1.
- The intersection point is (1, 2).
Step 3: The vertices of the triangle are (3, 0), (6, 0), and (1, 2).
Step 4: The base of the triangle lies on the x-axis, from x=3 to x=6. Base length = |6 - 3| = 3 units.
Step 5: The height of the triangle is the y-coordinate of the third vertex (1, 2), which is 2 units.
Step 6: Calculate the area of the triangle using the formula: Area = 1/2 * base * height. Area = 1/2 * 3 * 2 = 3 square units.
10
Determine the coordinates of the points where the graph of the equation 57x - 19y = 399 intersects the x and y coordinate axes.
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Solution: Step 1: To find the x-intercept, set y = 0 in the equation 57x - 19y = 399.
57x - 19*(0) = 399.
57x = 399.
x = 399 / 57.
x = 7.
The x-intercept is at the point (7, 0).
Step 2: To find the y-intercept, set x = 0 in the equation 57x - 19y = 399.
57*(0) - 19y = 399.
-19y = 399.
y = 399 / -19.
y = -21.
The y-intercept is at the point (0, -21).
11
A(7, -8) and C(1, 4) are opposite vertices of a square ABCD. Determine the equation of the diagonal BD.
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Solution: Step 1: Understand the properties of a square: its diagonals bisect each other at right angles. This means the diagonals AC and BD are perpendicular, and their midpoint is the same.
Step 2: Find the midpoint of diagonal AC, which will also be the midpoint of diagonal BD. Let A=(7, -8) and C=(1, 4).
Midpoint (x_m, y_m) = ((x1 + x2)/2, (y1 + y2)/2)
x_m = (7 + 1) / 2 = 8 / 2 = 4
y_m = (-8 + 4) / 2 = -4 / 2 = -2
The midpoint of both diagonals is (4, -2).
Step 3: Find the slope of diagonal AC.
Slope (m_AC) = (y2 - y1) / (x2 - x1) = (4 - (-8)) / (1 - 7) = (4 + 8) / -6 = 12 / -6 = -2.
Step 4: Find the slope of diagonal BD. Since diagonals are perpendicular, m_AC * m_BD = -1.
-2 * m_BD = -1 => m_BD = 1/2.
Step 5: Use the point-slope form (y - y1 = m(x - x1)) for diagonal BD, with the midpoint (4, -2) and slope m_BD = 1/2.
y - (-2) = (1/2)(x - 4)
y + 2 = (1/2)(x - 4)
Step 6: Multiply both sides by 2 to clear fractions:
2(y + 2) = x - 4
2y + 4 = x - 4
Step 7: Rearrange to the standard form: x - 2y = 4 + 4 => x - 2y = 8.
13
Calculate the area (in square units) enclosed by the lines x = 0, y = 0, x + y = 1, and 2x + 3y = 6.
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Solution: Step 1: Identify the intercepts of the lines on the x and y axes to define two triangles with the origin.
For line x + y = 1:
- When y = 0, x = 1. Point: (1, 0).
- When x = 0, y = 1. Point: (0, 1).
This line forms a small triangle with the origin (0,0) and the axes. The vertices are (0,0), (1,0), (0,1).
Area of this small triangle (Area_small) = (1/2) * base * height = (1/2) * 1 * 1 = 0.5 square units.
For line 2x + 3y = 6:
- When y = 0, 2x = 6 ⇒ x = 3. Point: (3, 0).
- When x = 0, 3y = 6 ⇒ y = 2. Point: (0, 2).
This line forms a large triangle with the origin (0,0) and the axes. The vertices are (0,0), (3,0), (0,2).
Area of this large triangle (Area_large) = (1/2) * base * height = (1/2) * 3 * 2 = 3 square units.
Step 2: The area bounded by the four given lines (x=0, y=0, x+y=1, 2x+3y=6) is the area of the region between the two lines x+y=1 and 2x+3y=6, in the first quadrant, bounded by the axes. This can be found by subtracting the area of the smaller triangle from the area of the larger triangle.
Required Area = Area_large - Area_small.
Required Area = 3 - 0.5 = 2.5 square units.
In fractional form, this is 5/2 or 2 1/2 square units.
14
Find the coordinates of the centroid for a triangle with vertices A(2, 5), B(-4, 0), and C(5, 4).
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Solution: Step 1: Recall the formula for the centroid of a triangle with vertices (x1, y1), (x2, y2), and (x3, y3):
Centroid (X, Y) = ((x1 + x2 + x3)/3, (y1 + y2 + y3)/3)
Step 2: Identify the given vertex coordinates:
A = (2, 5) => x1 = 2, y1 = 5
B = (-4, 0) => x2 = -4, y2 = 0
C = (5, 4) => x3 = 5, y3 = 4
Step 3: Calculate the x-coordinate of the centroid:
X = (2 + (-4) + 5) / 3 = (2 - 4 + 5) / 3 = 3 / 3 = 1
Step 4: Calculate the y-coordinate of the centroid:
Y = (5 + 0 + 4) / 3 = 9 / 3 = 3
Step 5: The coordinates of the centroid are (1, 3).
15
Determine the value of x, given that the line connecting points (-3, 4) and (0, 3) is perpendicular to the line connecting points (5, 7) and (4, x).
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Solution: Step 1: Calculate the slope (m1) of the first line passing through (-3, 4) and (0, 3).
m1 = (3 - 4) / (0 - (-3)) = -1 / 3.
Step 2: Calculate the slope (m2) of the second line passing through (5, 7) and (4, x).
m2 = (x - 7) / (4 - 5) = (x - 7) / -1 = -(x - 7).
Step 3: Since the lines are perpendicular, the product of their slopes is -1 (m1 * m2 = -1).
(-1/3) * (-(x - 7)) = -1.
Step 4: Simplify the equation.
(x - 7) / 3 = -1.
Step 5: Solve for x.
x - 7 = -3.
x = -3 + 7.
x = 4.
17
Which of the given points does the straight line represented by the equation y = 3x always pass through?
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Solution: Step 1: To determine if a point lies on a line, substitute its coordinates (x, y) into the equation of the line. If the equation holds true, the point lies on the line.
Step 2: Test the point (0, 0): Substitute x = 0 and y = 0 into the equation y = 3x.
0 = 3(0)
0 = 0.
Step 3: Since the equation holds true, the line y = 3x passes through the point (0, 0).
20
The line 3x + 4y = 24 intersects the x-axis at point A and the y-axis at point B. P(2, 0) and Q(0, 3/2) are points on segments OA and OB, respectively, where O is the origin. If AB = 10 cm, what is the length of PQ?
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Solution: Step 1: Find the x-intercept (point A) by setting y = 0 in the equation 3x + 4y = 24.
3x + 4(0) = 24 => 3x = 24 => x = 8. So, A = (8, 0).
Step 2: Find the y-intercept (point B) by setting x = 0 in the equation 3x + 4y = 24.
3(0) + 4y = 24 => 4y = 24 => y = 6. So, B = (0, 6).
Step 3: Identify the given points P(2, 0) and Q(0, 3/2). (Note: The information AB = 10 cm is consistent but not strictly needed to find PQ. Distance AB = sqrt((8-0)^2 + (0-6)^2) = sqrt(64+36) = sqrt(100) = 10.)
Step 4: Use the distance formula to find the length of PQ, where P=(x1, y1)=(2, 0) and Q=(x2, y2)=(0, 3/2).
Distance PQ = sqrt((x2 - x1)^2 + (y2 - y1)^2)
Step 5: Substitute the coordinates:
PQ = sqrt((0 - 2)^2 + (3/2 - 0)^2)
PQ = sqrt((-2)^2 + (3/2)^2)
PQ = sqrt(4 + 9/4)
PQ = sqrt(16/4 + 9/4)
PQ = sqrt(25/4)
PQ = 5/2
Step 6: Convert to decimal: PQ = 2.5 cm.