若a-b=3,ab=-1,则式子3ab-a b-2
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(2-ab+2a+5b)-(3ab+2b-2a)-(3a+4b-ab)=2-ab+2a+5b-3ab-2b+2a-3a-4b+ab=a-b-4ab+2=4-4+2=2
(-2ab+2a+3b)-(3ab+2b-2a)-(a+4b+ab)=-2ab+2a+3b-3ab-2b+2a-a-4b-ab=-6ab+3a-3b=-6ab+3(a-b)=6
(-2ab+2a+3b)-(3ab+2b-2a)-(a+4b+ab)=-2ab+2a+3b-3ab-2b+2a-a-4b-ab=-6ab+3a-3b=-6ab+3(a-b)=-6*1+3*4=-6+1
(-2ab+2a+3b)-(3ab+2b-2a)-(a+4b+ab)=-2ab+2a+3b-3ab-2b+2a-a-4b-ab=(-2ab-3ab-ab)+(2a+2a-a)+(3b-2b-4b)=-
(3a-4b-ab)-(a-2b+3ab)=3a-4b-ab-a+2b-3ab=2a-2b-4ab=2(a-b)-4ab=2×(-1)-4×(-2)(将a-b=-1,ab=-2代入)=-2+8=6
再问:不对是错的是-3再答:哪的题再问:暑假作业上的题再答:再答:答案错了用二项式定理你看一眼我写的
1.(A-B)+A*A+B*B+AB=(A-B)+A*A-2AB+B*B+3AB=(A-B)+(A-B)(A-B)+3AB=3-根号22.(X-1/X)的平方=X的平方-2+(1/X)的平方=X的平方
把a+b=1,ab=-2代入(-2ab+10a+3b)-3(ab-a-2b)+2(a+3b+ab)=(-2*-2+10a+3b)-3*(-2-a-2b)+2(a+3b-2)=4+10a+3b+3a+2
由条件去分母得a^2+b^2=3ab,代入合并约分得2
(5a-5b-ab)-(4a-6b-3ab)=5a-5b-ab-4a+6b+3ab=a+b+2ab=3-2x2=-1
1+a+ab+b=1+a+b(a+1)=(1+a)(1+b)
由1-2(a+ab)+(ab-2b)=3A1-2a-2ab+ab-2b=3A1-2(a+b)-ab=3A1-2A-(A+2008)=3A1-2A-A-2008=3A6A=-2007A=-334.5a+
(22a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)=22a+3b-2ab-a-4b-ab-3ab-2b+2a=23a-3b-5ab题目抄差了!(22a+3b-2ab)应该是(2a+3
最后等于4,关键就在于-a-b那里要添括号变成-(a+b)就好
ab+ba=a2+b2ab=(a+b)2−2abab,∵a+b=3,ab=1,∴(a+b)2−2abab=9-2=7,故答案为7.
(2a-3b-ab)-(a-2b+3ab)=2a-3b-ab-a+2b-3ab=a-b-4ab=-1-4×(-2)=7
1-2(a+ab)+(ab-2b)=1-2(a+b)-ab=1-2A-A-2008=3A,A=-669/2,所以a+b=-669/2,ab=-3347/2☆⌒_⌒☆诚心为您解答每一个问题!您的好评是我
原式=-2ab+10a+3b-3ab+3a+6b+2a+6b+2ab=15a+15b-3ab=15(a+b)-3ab=15×1-3×(-2)=21
原式=2a+3b-2ab-a-4b-ab-3ab-2b+2a=3a-3b-6ab=3(a-b)-6ab=3*3-6*1=3
a+b=3ab2a+2b-ab=6ab-ab=5aba+b+2ab=5ab所以原式=1