已知：x=五又七分之四,y=四又七分之三,求代数式[-三又二分之一(x+y)]^3×(x-y)×[-2(x-y)(x+y)]^2的值

题目

已知：x=五又七分之四,y=四又七分之三,求代数式[-三又二分之一(x+y)]^3×(x-y)×[-2(x-y)(x+y)]^2的值

答案

x=5+4/7,y=4+3/7x+y=9+7/7=10x-y=1+1/7=8/7[(-3-1/2)(x+y)]^3 * (x-y) * [-2(x-y)(x+y)]^2=-(7/2)^3 * (-2)^2 * (x+y)^3 * (x-y) * (x-y)^2 * (x+y)^2=-7^3 /2 * (x+y)^5 * (x-y)^3=-7^3 /2 * 10^5 * (8/7)^3=-7^3 /...