Răspuns :
x^2+3x+5x+15 =x^2+7x-x-7+10
x^2+8x-x^2-6x=3-15
2x=-12
x=-6
x^2-25=x^2+3x+x+3+12
x^2-x^2-4x=15+25
-4x=40
-x=10
x=-10
x^2+8x-x^2-6x=3-15
2x=-12
x=-6
x^2-25=x^2+3x+x+3+12
x^2-x^2-4x=15+25
-4x=40
-x=10
x=-10