Question

Can someone help me w this question plz.

Answer 1

For any solution it follows that y=y so:

x^2+2x=3x+20  subtract 3x from both sides

x^2-x=20  subtract 20 from both sides

x^2-x-20=0  factor...

x^2-5x+4x-20=0

x(x-5)+4(x-5)=0

(x+4)(x-5)=0

x=-4 and 5  now to find the corresponding y values I'll use y=x^2+2x

y(-4)=16-8=8 and y(5)=25+10=35  so the two solutions are the points:

(-4, 8) and (5, 35)