A line passes through (-1,7) and (2,10). Which is the equation of the line?

A.-3x + y = 16
B -3x+y=4
C -x+y=12
D -x+y=8

Question

A line passes through (-1,7) and (2,10). Which is the equation of the line?

A.-3x + y = 16
B -3x+y=4
C -x+y=12
D -x+y=8

anonymous · Answer

well given that this problem is a multiple choice problem there's a brute force method and the actual solving for the equation method, which do you prefer?

anonymous · Answer

Brute force? lol

anonymous · Answer

ok well you can just simply plug in those points into the equations to see if they work, after all if they lie within the line they should work in the equation.

anonymous · Answer

D. -x+y=8?

anonymous · Answer

yup! that works doesn't it? Would you like to know the other method or are you good?

anonymous · Answer

The other method would help because I have a few more of these questions! :)

anonymous · Answer

haha yes it would. Well you probably know the equation of a line as y =mx+b right?

anonymous · Answer

Mhm. I actually had to double-check because I was graphing each equation to see. My graphing matched up with letter D, but your tip was a lot quicker and easier.

anonymous · Answer

ahhh I see well there's another form of the line equation given like this: $$y-y _{1} = m(x-x _{1})$$ have you seen this equation?

anonymous · Answer

Mhm, I have a few times.

anonymous · Answer

well it's called the point-slope form of an equation. And it can be used to find the equation of a line given you know a point and the slope of the line. Do you know how to solve for the slope of a line?