How do you solve y=x2+2x3 and y=x-5?

1 Answer
Sep 6, 2015

(-1, - 6)
(2, - 3)

Explanation:

y=x2+2x3 ------------------(1)
This is a downward facing U shaped curve
y = x - 5 -------------------------(2)
Straight line cuts it at two points.

Substitute y=x2+2x3 in equation (2)

x2+2x3=x5
x2+2x3x+5=0
x2+x+2=0
x2+2xx+2=0
x ( - x + 2) + 1 (- x +2) = 0
(x + 1) ( - x + 2) = 0
(x + 1 = 0
x = -1

  • x + 2 = 0
    x = 2
    Substitute the x values in equation (1)
    At x = - 1 ; y = -1 - 5 = - 6

(- 1, -6) one point

At x = 2 ; y = 2 - 5 = 3

(2, -3) is another point

Refer the graph