Răspuns :
x^2+2x-(6x^2+8x+9x+12)=18-5x^2
x^2+2x-(6x^2+17x+12)=18-5x^2
x^2+2x-6x^2-17x-12=18-5x^2
-5x^2-15x-12=18-5x^2
-15x-12=18
-15x-12-18=0
-15x-30=0
x+2=0
x=-2
Răspuns:
-2
Explicație pas cu pas:
x²+2x-(6x²+9x+8x+12)=18-5x²
x²+2x-6x²-17x-12=18-5x²
-15x=18+12 15x=-30 x=-2