Which rule represents linear decay and also has initial value 60?
Answer and explanation
Correct answer: y = 60 - 4x
A linear decay rule has the form y=a-bx with b>0: it is linear, its slope is negative, and its initial value at x=0 is a. In option A, y=60-4x, the initial value is 60 and the slope is -4, so the quantity decreases steadily. Option B grows, option C starts at 4, and option D is quadratic with initial value -60.
Frequently asked questions
What is the correct answer to this question?
y = 60 - 4x
Why is this the correct answer?
A linear decay rule has the form y=a-bx with b>0: it is linear, its slope is negative, and its initial value at x=0 is a. In option A, y=60-4x, the initial value is 60 and the slope is -4, so the quantity decreases steadily. Option B grows, option C starts at 4, and option D is quadratic with initial value -60.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Linear growth and decay.
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