Question

How do I solve this system of equations by substitution?
y - 3x = 2, y=(x + 1)^2 - 5

Answer 1

Hello,

y-3x=2==>x=(y-2)/3
==>(x+1)²=((y-2)/3+1)²=(y+1)²/9

y=(x+1)²-5
==>y=(y²+2y1)/9 -5
==>y²-7y-44=0 ; Δ=7²+4*44=225=15²
==>y=(7+15)/2 or y=(7-15)/2

==>y =11 and x=(11-2)/3=3
or y=-4 and x=(-4-2)/3=-2

sol={(3,11);(-2,-4)}