Question

What is the y-intercept of a line that has a slope of 3 and passes through point (–1, –7)? A.–10 B.–4 C.3 D.7

Answer 1

Answer: B . -4

Explanation:

The equation of line passing through point (a,b) and having slope m is given by :-

`(y-b)=m(x-a)`

Given : Slope of line= 3

Point = (-1,-7)

Now, the equation of line passing through point (-1,-7) and having slope 3 is given by :-

`(y-(-7))=3(x-(-1))\\\\\Rightarrow\ (y+7)=3(x+1)`

To find the y-intercept , put x=0 , we get

`(y+7)=3(0+1)\\\\\Rightarrow\ y+7=3\\\\\Rightarrow\ y=3-7=-4`

Hence, the y-intercept of a line that has a slope of 3 and passes through point (-1, -7) = -4

Answer 2

The point-slope form of the line's equation can be written as
y = 3(x +1) -7
and simplified to
y = 3x -4

The y-intercept is ...
B. -4