Question

已知a+c=b/x-dx a-c=d/x-bx 且｜a｜不等于｜b｜ 求c^2/(b-d)^2-a^2/(b+d)^2=

Answer 1

1,两式相加得 a=(1/2)(1/x -x)(b+d)

2.两式相减得 c=(1/2)(x+1/x)(b-d)

a^2/(b-d)^2=(1/4)(1/x-x)^2=(1/4)(1/(x^2) +x^2-2)

c^2/(b-d)^2=(1/4)(x- 1/x)^2=(1/4)(x^2 +1/(x^2) +2)

下式减上式就等于1了