Find the point at which the line f(x) = -4x-9 intersects the line g(x) =4x+15.

Answer 1

-4x - 9 = 4x + 15

Can you sovle for x and answer?

Answer 2

4x + 15 = -4x -9

8x = -24

x = -24/8 = -3

y = 4(-3) +15 = -12 +15 = 3

(x,y) = (-3,3) = point where the two lines intersect

that's the algebra method

or use a graphing calculator

or sketch the graph yourself

one line is upward sloping with slope =4 and y intercept =15

other line is downward sloping with slope =-4 and y intercept = -9

a rough sketch tells you they intersect in quadrant 2, with negative x coordinate and positive y coordinate, as in (-3,3)