Question

Which is not an equation of the line going through (6,7) and (2,-1) A. y-7=2(x-6) B. y=2x-5 C. y-1=2(x+2) D. y+1=2(x-2)

Answer 1

Answer:

C. y-1=2(x+2)

Step-by-step explanation:

A. y-7=2(x-6)-point slope form: y-y1=2(x-x1)-coordinate point: (x1,y1)=(6,7)

Now let's check that the other point works-just sub in the coordinates for the x and y variables.

y-7=2(x-6)\\-1-7=2(2-6)\\-8=2(-4)\\-8=-8

So answer choice A. goes through both points, so no.

B. y=2x-5-slope-intercept form, so just sub in both sets of coordinates separately to see if they each work.

y=2x-5\\7=2(6)-5\\7=12-5\\7=7\\equal

y=2x-5\\-1=2(2)-5\\-1=4-5\\-1=-1\\equal

Both work, so no.

C. y-1=2(x+2)-point slope form that gives us first coordinate set--(-2,1)

Except that the point is actually (2,-1) not (-2,1).  That means that answer choice C is not an equation of the line thaat goes through (6,7) and (2,-1), so yes.

D. Anyway, if we check D--y+1=2(x-2)--coordinate point given: (2,-1), which is correct, so no.