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先化简,后求值:(a-b/a+b)^2×(3a+3b/2a-2b)+a^2-b^2/ab,其中a=2,b=负1 【急~】
人气:283 ℃ 时间:2019-08-20 21:27:50
解答
:(a-b/a+b)^2×(3a+3b/2a-2b)+a^2-b^2/ab,
=(a-b)^2/(a+b)^2×(3/2*(a+b)/(a-b)+a^2-b^2/ab
=3/2(a-b)/(a+b)+(a-b)(a+b)/ab
=1/2(a-b)(3/(a+b)+2(a+b)/ab)
=1/2(2+1)(3/(2-1)+2(2-1)/2*(-1))
=3/2(3-2)
=3/2你再检查下算错了,应是 (a-b/a+b)^2×(3a+3b/2a-2b)+a^2-b^2/ab, =(a-b)^2/(a+b)^2×(3/2*(a+b)/(a-b)+a^2-b^2/ab =3/2(a-b)/(a+b)+(a-b)(a+b)/ab =1/2(a-b)(3/(a+b)+2(a+b)/ab) =1/2(2+1)(3/(2-1)+2(2-1)/2*(-1)) =3/2(3-1) =3恩恩、我算的也是3
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