When graphing a linear equation that is written in the form y=mx+b, the variable m represents the y-intercept. Assuming that b>0, which of the following best describes how reversing the sign of b would affect the graph?

A) The new line will be shifted down b units

B) The new line will be shifted down b x 2 units

C) The new line will be a perfect reflection across the x-axis

D) The new line will be a perfect reflection across the y-axis

Question

Bessie

SAT

13 December, 07:00

When graphing a linear equation that is written in the form y=mx+b, the variable m represents the y-intercept. Assuming that b>0, which of the following best describes how reversing the sign of b would affect the graph?

A) The new line will be shifted down b units

B) The new line will be shifted down b x 2 units

C) The new line will be a perfect reflection across the x-axis

D) The new line will be a perfect reflection across the y-axis

+4

Answers (1)

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Gabriel Cisneros · Answer 1

B. A numeric example of this is with a y-intercept of 7. Changing it to - 7 will cause a downwards shift of 14 units. This is because it takes 7 units to get down to 0, then another 7 to get to - 7.

A downwards shift of b units will always result in a new value of 0, so this is obviously not true. Reflection has nothing to do with the y-intercept, or b value. So beyond the mathematical explanation provided above, you could solve this using the process of elimination.