In the line (y=-8x+21), what change occurs in (y) when (x) increases by (1)?
Answer and explanation
Correct answer: Decreases by (8)
The equation is in the form y = mx + c, where the coefficient of x, m, is the slope. Here the slope is -8, so an increase of 1 in x produces a change of -8 in y; that is, y decreases by 8. The number 21 is the y-intercept, not the rate of change. Exam tip: identify the coefficient of x to find the slope directly.
Frequently asked questions
What is the correct answer to this question?
Decreases by (8)
Why is this the correct answer?
The equation is in the form y = mx + c, where the coefficient of x, m, is the slope. Here the slope is -8, so an increase of 1 in x produces a change of -8 in y; that is, y decreases by 8. The number 21 is the y-intercept, not the rate of change. Exam tip: identify the coefficient of x to find the slope directly.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Slope and y-intercept.
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