Explicație pas cu pas:
b)x○(3x-1)=6 => 2x+(3x-1)-3=6 => 5x-1-3=6 =>5x-4=6 =>5x=10=>x=2
c)(x+1)○3=5○(x²-8) =>
2(x+1)+3-3=2*5+(x²-8)-3
2x+2=10+x²-8-3
2x+2=x²-1 => 2x+2-x²+1=0 => -x²+2x+3=0 => -x²-x+3x+3=0 => -x(x+1)+3(x+1)=0 => (x+1)(3-x)=0 => x+1=0 sau 3-x=0 => x=-1 sau x=3 => x€{3,-1}
