Question

Choose the equation that represents a line that passes through points (-1,2) and (3,1)

A=4x-y=-6
B=x+4y=7
C=x-4y=-9
D=4x+y=2

Answer 1

They're all in standard form; it's probably easier just to solve for the line than check the points in each one.

The point-point form of a line through (a,b) and (c,d) is

(c-a)(y-b) = (d-b)(x-a)

So here (a,b)=(-1,2), (c,d)=(3,1) so

(3 - -1)(y - 2) = (1 - 2)(x - -1)

4y - 8 = -x - 1

x + 4y = 7

Answer: B

Check:

-1 + 4(2) = 7, good

3 + 4(1) = 7, good