Question

A line passes through (−1, 7) and (2, 10).

Which answer is the equation of the line?

A. −3x+y=4−3x+y=4

B. −3x+y=16−3x+y=16

C. −x+y=8−x+y=8

D. −x+y=12

Answer 1

Its -x+y=8.

Explanation:

I took the test. yw.

Answer 2

The slope m of a line through points
`A(x_1, y_1)` and
`B(x_2, y_2)` is given by :


`\displaystyle{m = (y_2-y_1)/(x_2-x_1)`



Thus, the slope of the line passing through points (−1, 7) and (2, 10) is


`\displaystyle{m= (10-7)/(2-(-1))= (3)/(3)=1`


The equation of a line with slope m passing through a point P(a, b) is given by
(y-b)=m(x-a).


We can consider any of the points (-1, 7), or (2, 10). Let's choose (2, 10):

y-10=1(x-2)
y-10=x-2
y-x=-2+10
y-x=8


Answer: C. −x+y=8