Question

初一 数学 数学因式分解 请详细解答,谢谢! (18 22:20:13)

已知a/x+2与b/x-2的和等于4x/x2-4，求a+b的值（详细过程）
 

Answer 1

a/(x+2)+b/(x-2)
=[a(x-2)+b(x+2)]/(x+2)(x-2)
=[(a+b)x+(2b-2a)]/(x²-4)
=4x/(x²-4)
所以(a+b)x+(2b-2a)=4x
即(a+b)x+(2b-2a)=4x+0
所以a+b=4

Answer 2

依题目，a/(x+2)+b/(x-2)=4x/(x^2-4),
[a(x-2)+b(x+2)]/(x^2-4)=4x/(x^2-4)
[(a+b)x-2a+2b]/(x^2-4)=4x/(x^2-4),
所以：a+b=4,-2a+2b=0,
所以a=b=2,
所以a+b=4

Answer 3

a/x+2+b/x-2
=[a(x-2)+b(x-2)]/(x^2-4)
=[(a+b)x-2(a-b)]/(x^2-4)

a+b=4
-2(a-b)=0

a=b=2

a+b=4

Answer 4

a/(x+2)+b/(x-2)=4x/(x^2-4)
[a(x-2)+b(x+2)]/[(x-2)(x+2)]=4x/(x^2-4)
(ax-2a+bx+2b)/(x^2-4)=4x/(x^2-4)
(a+b)x-2(a-b)=4x

a+b=4

Answer 5

a/x+2+b/x-2=4x/x2-4
解：a/x+b/x=4x/x2-8x/x2
2(a+d)/x2=(4x-8x)/x2
a+d=-2x

Answer 6

我用图片回答的,不知道能不能看清楚.