Question

The two lines y= 6x+15 and y= mx+4 intersect at x= -2. What is the y-coordinate of their intersection point

Answer 1

Answer:

The y-coordinate of their intersection point is 3

That is y=3

Step-by-step explanation:

Given two lines are y=6x+15 and y=mx+4

Given that the two lines intersect at x=-2

To find the y coordinate of their intersection point :

Equating the two lines

6x+15=mx+4

6x+15-mx-4=0

6x-mx+11=0

(6-m)x+11=0

At x=-2  (6-m)x+11=0

(6-m)(-2)+11=0

(6-m)(-2)=-11

$6-m=\frac{11}{2}$

$-m=\frac{11}{2}-6$

$-m=\frac{11-12}{2}$

$-m=\frac{-1}{2}$

$m=\frac{1}{2}$

Substitute the value $m=\frac{1}{2}$ in y=mx+4 we get

$y=\frac{1}{2}x+4$

At x=-2 $y=\frac{1}{2}(-2)+4$

$=-1+4$

$=3$

Therefore y=3

Therefore the y-coordinate of their intersection point is 3