Đáp án:
Giải thích các bước giải:
a, (2x+7)²+(5-2x)²-2x(2x-2)
=4x²+28x+49+25+4x²-20x-4x²+4x
=4x²+12x+74
b, (4x+1)²+(2-4x)²+(7x-1)($\frac{1}{14}$ +6x)
=16x²+8x+1+4+16x²-16x+$\frac{1}{2}$x+42x²-$\frac{1}{14}$-6x
=74x²-13,5x+$\frac{69}{14}$
c, (x+1)³+(x-1)³-2x³
=x³+3x²+3x+1+x³-3x²+3x-1-2x³
=6x
d, (2x+3)³-(3x-1)³+5x(x²-3)
=8x³+36x²+54x+27-(27x³-27x²+9x-1)+5x³-15x
=8x³+36x²+54x+27-27x³+27x²-9x+1+5x³-15x
=-14x³+63x²+30x+28