(10x^2+7x-6)^2+4+4(10x^2+7x-6)
=[(10x^2+7x-6)+2]^2
=(10x^2+7x-4)^2
=[10x^2+(7x-4)]^2
=(10x^2)^2+2*10x^2(7x-4)+(7x-4)^2
=10x^4+140x^3-80x^2+49x^2-56x+16
=10x^4+140x^3-31x^2-56x+16