1)x+3Vx-10= (Vx+1,5)^2-12,25=(Vx+1,5)^2-3,5^2=(Vx+1,5-3,5)*(Vx+1,5+3,5)=(Vx-2)(Vx+5)
V- знак квадратного корня
2)7x^4+3x^3-10= 7x^4+3x^3-7-3= (7x^4-7)+(3x^3-3)= 7(x^4-1)+3(x^3-1)=7(x^2-1)(x^2+1)+3(x-1)(x^2+x+1)= 7(x-1)(x+1)(x^2+1) +3(x-1)(x^2+x+1)= (x-1)*[7(x+1)*(x^2+1)+3(x^2+x+1)]=(x-1)*[7(x^3+x+x^2+1)+3x^2+3x+3]=(x-1)(7x^3+7x+7x^2+7+3x^2+3x+3)=(x-1)(7x^3+10x^2+10x+10)