Question

A student writes the equation for a line that has a slope of -6 and passes through the point (2, –8).

y -(-8) = -6(x - 2)

y -(-8) = -6x + 12

y -(-8) + 8 = -6x + 12 + 8

y = -6x + 20      explain why its not correct

Answer 1

In the third step, y-(-8) is the same as y+8. Therefore, it is not correct to add 8 on to both sides. Instead, the student should have subtracted it from both sides.

y-(-8)=-6x+12
y+8=-6x+12
y=-6x+4