(2x-y-3)(2x-y+3)-(2x-y-3)^2 已知a-1/2=2,求a^2+1/a^2,a^4+1/a^4的值 ,答案和步骤?要认真回答哦!谢谢

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(2x-y-3)(2x-y+3)-(2x-y-3)^2 已知a-1/2=2,求a^2+1/a^2,a^4+1/a^4的值 ,答案和步骤?要认真回答哦!谢谢

(2x-y-3)(2x-y+3)-(2x-y-3)^2 已知a-1/2=2,求a^2+1/a^2,a^4+1/a^4的值 ,答案和步骤?要认真回答哦!谢谢
(2x-y-3)(2x-y+3)-(2x-y-3)^2 已知a-1/2=2,求a^2+1/a^2,a^4+1/a^4的值 ,答案和步骤?要认真回答哦!谢谢

(2x-y-3)(2x-y+3)-(2x-y-3)^2 已知a-1/2=2,求a^2+1/a^2,a^4+1/a^4的值 ,答案和步骤?要认真回答哦!谢谢
(2x-y-3)(2x-y+3)-(2x-y-3)²
=(2x-y-3)[(2x-y+3)-(2x-y-3)]
=6(2x-y-3)
a-1/a=2
a²+1/a²=(a-1/a)²+2=2²+2=6
a^4+1/a^4=(a^2+1/a^2)²-2=6²-2=36-2=34

a-1/2=2
a=5
a²+1/a²=26/25
a^4+1/a^4=626/625

那个你的a的值不是已经给出了吗?。。