已知:x等于4,y等于负八分之一,求代数式七分之1xy的平方乘十四括号xy的平方乘四分之一x的5方.怎么求的?

Question

已知:x等于4,y等于负八分之一,求代数式七分之1xy的平方乘十四括号xy的平方乘四分之一x的5
方.怎么求的?

Answer 1

X=4,y=-1/8
1/7xy^2 × 14 (xy)^2 × 1/4 x^5
= ( 1/7× 14 × 1/4 ) × { xy^2 × (xy)^2 × x^5 }
= 1/2 × { xy^2 × x^2 × y^2 × x^5 }
= 1/2 × { x^8 × y^4 }
= 1/2 × { x^4 ×(x×y)^4 }
= 1/2 × { 4^4 ×(4×(-1/8))^4 }
= 1/2 × { 4^4 ×(-1/2)^4 }
= 1/2 × (4^ ×(-1/2) }^4
= 1/2 × (-2)^4
= 1/2 × 16
= 8