2a^2-(4b^2+2ab)+(3b^2-2a^2-3ab),其中a=5分之2,b=--3为什么我算来算去都=--3
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2a^2-(4b^2+2ab)+(3b^2-2a^2-3ab),其中a=5分之2,b=--3
为什么我算来算去都=--3
先化简,再求值
2a²-(4b²+2ab)+(3b²-2a²-3ab)
=2a²-4b²-2ab+3b²-2a²-3ab
=(2a²-2a²)+(-4b²+3b²)+(-2ab-3ab)
=-b²-5ab
将a=2/5,b=-3代入
原式=-b²-5ab=-(-3)²-5*2/5*(-3)=-3
2a^2-(4b^2+2ab)+(3b^2-2a^2-3ab)
=2a^2-4b^2-2ab+3b^2-2a^2-3ab
=2a^2-2a^2-4b^2+3b^2-2ab-3ab
=-b^2-5ab
=-(-3)^2-5*2/5*(-3)
=-9+6
=-3
2a^2-(4b^2+2ab)+(3b^2-2a^2-3ab),
=2a²-4b²-2ab+3b²-2a²-3ab
=-b²-5ab
当a=2/5,b=-3时
原式=-9+6=-3
2a^2-(4b^2+2ab)+(3b^2-2a^2-3ab),
=2a^2-4b^2-2ab+3b^2-2a^2-3ab
=-b²-5ab
=-(-3)²-5×5分之2×(-3)
=-9+6
=-3
2a^2-(4b^2+2ab)+(3b^2-2a^2-3ab)
=2a^2-4b^2-2ab+3b^2-2a^2-3ab
=-b^2-5ab
=-b(b+5a)
将a=2/5,b=-3代入上式,得-(-3)*[(-3)+5*2/5]=3*[-3+2]=3*(-1)=-3
(a-b)^3+2ab(a-b)
a^2b-ab+2ab^2-5a^b-4ab+3ab^2化简快
1/4a^2b^2{3ab(a+b)-5a(ab-b^2)}=?
(a-b)(a^5+a^4b+a^3b^2+ab^4+b^5)bggg
a+b/2ab
2AB/A+B
a+b/2ab
4ab/b^2(a-b)=
ab^3+b^2+b-a+1
2a²b(a-b)+ab(a-b)²+4ab²(a-b)
-2ab(3a^2-2ab-4b^2) (2b-a)b-(2a-b)a-2ab(3a^2-2ab-4b^2)(2b-a)b-(2a-b)a
-4a^3b+6a^2b-2ab
ab/a+b=3 a-2ab+b/2a-3ab+2b?
(a-b)(3ab+2a²b-b³)
5ab^2-{2a^b-[3ab^2-(4ab^2-2a^2b)]}
{ab-[3a²b-(4a²b+1/2ab)]-4a²b}+3a²b
计算(3a-2b)(9a*a+6ab+4b*b)-(3a+2b)(9a*a-6ab+4b*b)
已知a-b=5,ab=-4,求代数式5a^2b(a-b)-3ab(b-a)^2+5ab^2(b-a)的值