高考问答microsoft office x64:解答题.....
来源：百度文库 编辑：高考问答 时间：2024/04/29 18:08:49
1.已知x+1/x=2,求x²+1/x²,x^4+1/x^4的值
2.已知(a-1)(b-2)-a(b-3)=3，求代数式[(a²+b²)/2]-ab的值
2.已知(a-1)(b-2)-a(b-3)=3，求代数式[(a²+b²)/2]-ab的值
1.x²+1/x²=（x+1/x）²-2=4-2=2
x^4+1/x^4=（x²+1/x²）²-2=4-2=2
2.(a-1)(b-2)-a(b-3)=3
ab-2a-b+2-ab+3a=3
a-b=1
[(a²+b²)/2]-ab
=(a²-2ab+b²)/2
=(a-b)²/2
=1/2