10 questions · Form 4 Additional Mathematics Bab 6: Linear Law
A graph of y² against x has a gradient of -2 and passes through (4, 10). What is the value of the vertical intercept c?
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1. A graph of y² against x has a gradient of -2 and passes through (4, 10). What is the value of the vertical intercept c?
Answer: A
Y = mX + c => 10 = -2(4) + c => 10 = -8 + c => c = 18.
2. A straight line plot of lg y against x has a Y-intercept of 0.6021. Find the value of constant a if y = a b^x.
Answer: A
c = lg a = 0.6021 => a = 100.6021 ≈ 4.
3. Given the equation y = a √x + b/√x, which transformation yields a straight line with Y-intercept b when plotted against x?
Answer: A
Multiply y = a√x + b/√x by √x: y√x = ax + b. Plotted Y = y√x against X = x, gradient m = a and vertical intercept c = b.
4. If y - x = p x² + q, what variables should be plotted on the vertical and horizontal axes to obtain a straight line with gradient p?
Answer: A
Comparing y - x = p x² + q with Y = mX + c gives Y = y - x, X = x², gradient m = p, and intercept c = q.
5. Variables x and y are connected by p^x y = q. Express this in linear form Y = mX + c.
Answer: A
Take lg on both sides: lg(p^x y) = lg q => x lg p + lg y = lg q => lg y = (-lg p)x + lg q.
6. Convert the non-linear equation y = ax² + bx into linear form Y = mX + c when plotting yx against x.
Answer: A
Dividing both sides of y = ax² + bx by x gives yx = ax + b. Comparing with Y = mX + c gives Y = yx, X = x, gradient m = a, and vertical intercept c = b.
7. Variables x and y are related by y = ax + b. A graph of xy against x gives a straight line with gradient 4 and y-intercept 6. Find the values of a and b.
Answer: A
Multiply y = ax + b by x: xy = bx + a. Thus Y = xy, X = x, gradient m = b = 4, and intercept c = a = 6.
8. The variables x and y satisfy y = h x^k. When lg y is plotted against lg x, the line passes through (0, 1) and (2, 7). Find the value of k.
Answer: A
Equation: lg y = k lg x + lg h. Gradient m = 7 - 12 - 0 = 62 = 3. Since gradient m = k, k = 3.
9. A plot of lg y against lg x gives a line with gradient m = 0.5 and Y-intercept c = 0.3010. Express y in terms of x.
Answer: A
lg y = 0.5 lg x + 0.3010 => lg y = lg(x0.5) + lg(100.3010) = lg(x0.5) + lg 2 = lg(2√x) => y = 2√x.
10. Variables x and y are related by y = 2x² + kx. When xy is plotted against x³, the graph is a straight line. What is the vertical intercept?
Answer: A
Multiply y = 2x² + kx by x: xy = 2x³ + k. Comparing with Y = mX + c where Y = xy and X = x³ gives gradient m = 2 and vertical intercept c = k.