Đáp án:
a) (x+2)² – (x+3)(x-3) + 10
=x²+4x+4-x²+9+10
=4x+23
b) (x+5)(x² – 5x + 25) – x(x-4)² + 16x
=x³+125-x(x²-8x+16)+16x
=x³+125-x³+8x²-16x+16x
=125+8x²
c) (x-2y)³ – (x+2y)(x² – 2xy + 4y²) + 6x²y
=x³-6x²y+12xy²-8y³-x³-8y³+6x²y
=x³-x³-6x²y+6x²y-8y³-8y³+12xy²
=12xy²-16y³