.(2X-5Y)²（5X+2Y）².
=[ (2X-5Y)（5X+2Y）]²
=（10X² - 21XY + 10Y²）²
=100x^4 -420yx^3+641X²Y²-420xy^3+100y^4
（x^2+2x）^2-11(x^2+2x)+24
令x^2+2x=t
原式=t^2-11t+24
=t^2-(8+3)t+8*3
=(t-3)(t-8)
=(x^2+2x-3)(x^2+2x-8)
=[x^2+(3+(-1))x+3*(-1)][x^2+(4+(-2))x+4*(-2)]
=(x-1)(x+3)(x-2)(x+4)