If (y=150-6x), what happens to (y) when (x) increases from (3) to (13)?
Answer and explanation
Correct answer: It decreases by 60
As x changes from 3 to 13, the change in x is 10. In y = 150 - 6x, the coefficient of x is -6, so y decreases by 6 for every increase of 1 in x. Therefore, the total change in y is -6 × 10 = -60; hence, y decreases by 60. Checking directly, y(3) = 132 and y(13) = 72. The value 78 is not the final value of y, and y does not increase. Exam tip: In a linear equation, total change = coefficient of x × change in x.
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What is the correct answer to this question?
It decreases by 60
Why is this the correct answer?
As x changes from 3 to 13, the change in x is 10. In y = 150 - 6x, the coefficient of x is -6, so y decreases by 6 for every increase of 1 in x. Therefore, the total change in y is -6 × 10 = -60; hence, y decreases by 60. Checking directly, y(3) = 132 and y(13) = 72. The value 78 is not the final value of y, and y does not increase. Exam tip: In a linear equation, total change = coefficient of x × change in x.
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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