a/(x+2)与b/(x-2)的和为4x/(x的2次幂-4),a=?,b=?得到2元一次方程a+b=4a-b=0为什么一定要a+b=4!
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![a/(x+2)与b/(x-2)的和为4x/(x的2次幂-4),a=?,b=?得到2元一次方程a+b=4a-b=0为什么一定要a+b=4!](/uploads/image/z/2556481-49-1.jpg?t=a%2F%28x%2B2%29%E4%B8%8Eb%2F%28x-2%29%E7%9A%84%E5%92%8C%E4%B8%BA4x%2F%28x%E7%9A%842%E6%AC%A1%E5%B9%82-4%29%2Ca%3D%3F%2Cb%3D%3F%E5%BE%97%E5%88%B02%E5%85%83%E4%B8%80%E6%AC%A1%E6%96%B9%E7%A8%8Ba%2Bb%3D4a-b%3D0%E4%B8%BA%E4%BB%80%E4%B9%88%E4%B8%80%E5%AE%9A%E8%A6%81a%2Bb%3D4%21)
a/(x+2)与b/(x-2)的和为4x/(x的2次幂-4),a=?,b=?得到2元一次方程a+b=4a-b=0为什么一定要a+b=4!
a/(x+2)与b/(x-2)的和为4x/(x的2次幂-4),a=?,b=?
得到2元一次方程
a+b=4
a-b=0
为什么一定要a+b=4!
a/(x+2)与b/(x-2)的和为4x/(x的2次幂-4),a=?,b=?得到2元一次方程a+b=4a-b=0为什么一定要a+b=4!
a/(x+2)+b/(x-2)=4x/(x的2次幂-4),
(ax-2a+bx+2b)/(x²-4)=4x/(x²-4)
分子相等得:
(a+b)x-2(a-b)=4x
系数对应相等得:
a+b=4
a-b=0
解得:a=b=2
a/(x+2)+b/(x-2)=4x/(x^2-4)
a(x-2)/(x-2)(x+2)+b(x+2)/(x-2)(x+2)=4x/(x-2)(x+2)
[a(x-2)+b(x+2)]/(x-2)(x+2)=4x/(x-2)(x+2)
(ax-2a+bx+2b)/(x-2)(x+2)=4x/(x-2)(x+2)
(ax+bx-2a+2b)/(x-2)(x+2)=4x/(x-2)(x+2)
[(a+b)x-2(a-b)]/(x-2)(x+2)=4x/(x-2)(x+2)
所以
a+b=4
a-b=0