1立方和与立方差公式1、(a+b)(a2-ab+b2)=a3+b3两数的和乘以它们的平方和与它们的积的差,等于这两个数的立方和.2、(a-b)(a2+ab+b2)=a3-b3两数的差乘以它们的平方和与它们的积的和,等于这两个数的立方差.例计算:(1)(3+2y)(9-6y+4y2);(2)(5a-21b2)(25a2+41b4+25ab2);(3)(4)课堂练习1立方和或立方差公式:(1)(x-3)()=x3-27;(2)(2x+3)()=8x3+27;(3)(x2+2)()=x6+8;(4)(3a-2)()=27a3-82(1)()(a2+2ab+4b2)=__________;(2)()(9a2-6ab+4b2)=__________;(3)()(41-xy+4y2)=__________;(4)()(m4+4m2+16)=__________3、下列等式能够成立的是[]A.(a+b)(a2+2ab+b2)=a3+b3;B.(a-b)(a2-ab+b2)=a3-b3;C.(a-b)(a2+ab+b2)=a3-b3;D.(a-b)(a2+2ab+b2)=a3-b3.4、能够用立方和、立方差公式进行计算的是[]2A.(m+n)(m3+m2n+n3);B.(m-n)(m2+n2);C.(x+1)(x2-x+1);D.(x2+1)(x2-x+1)5(1)(y+3)(y2-3y+9);(2)(c+5)(25-5c+c2);(3)(2x-5)(4x2+25+10x)(4)(x2-y2)(x4+x2y2+y4)(5)(5-2y)(4y2+25+10y)(6)(2a+b)(4a2-4ab+b2)(7)(1+4x)(16x2+1-4x)(8)(x-1)(x2-x+1);(9)(a-3)(a2+3a-9)(10)(a-2b)(a+2b)(a2+2ab+4b2)(a2-2ab+4b2).6已知x2+y2=6,xy=2,求x6+y6的值.