求多项式2AB-AB^2+3与2AB+3AB-1的差a=-1,b=1时,求(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)的值已知A=a^2-2a+1,B=-3a^2-4a+2,求当a=-1时,3A-B的值
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![求多项式2AB-AB^2+3与2AB+3AB-1的差a=-1,b=1时,求(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)的值已知A=a^2-2a+1,B=-3a^2-4a+2,求当a=-1时,3A-B的值](/uploads/image/z/2666163-3-3.jpg?t=%E6%B1%82%E5%A4%9A%E9%A1%B9%E5%BC%8F2AB-AB%5E2%2B3%E4%B8%8E2AB%2B3AB-1%E7%9A%84%E5%B7%AEa%3D-1%2Cb%3D1%E6%97%B6%2C%E6%B1%82%283a%5E2-2ab%2B2b%5E2%29-%282a%5E2-b%5E2-2ab%29%E7%9A%84%E5%80%BC%E5%B7%B2%E7%9F%A5A%3Da%5E2-2a%2B1%2CB%3D-3a%5E2-4a%2B2%2C%E6%B1%82%E5%BD%93a%3D-1%E6%97%B6%2C3A-B%E7%9A%84%E5%80%BC)
求多项式2AB-AB^2+3与2AB+3AB-1的差a=-1,b=1时,求(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)的值已知A=a^2-2a+1,B=-3a^2-4a+2,求当a=-1时,3A-B的值
求多项式2AB-AB^2+3与2AB+3AB-1的差
a=-1,b=1时,求(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)的值
已知A=a^2-2a+1,B=-3a^2-4a+2,求当a=-1时,3A-B的值
求多项式2AB-AB^2+3与2AB+3AB-1的差a=-1,b=1时,求(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)的值已知A=a^2-2a+1,B=-3a^2-4a+2,求当a=-1时,3A-B的值
(2AB-AB^2+3)-(2AB+3AB-1)
=2AB-AB^2+3-2AB-3AB+1
=-AB^2-3AB+4;
(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)
=3a^2-2ab+2b^2-2a^2+b^2+2ab
=a^2+3b^2,
当a=-1,b=1时,
原式=a^2+3b^2
=(-1)^2+3*1^2
=1+3
=4;
因为A=a^2-2a+1,B=-3a^2-4a+2,
所以3A-B=3(a^2-2a+1)-(-3a^2-4a+2)
=3a^2-6a+3+3a^2+4a-2
=6a^2-2a+1,
当a=-1时,
原式=6a^2-2a+1
=6*(-1)^2-2*(-1)+1
=6*1+2+1
=6+2+1
=9.
条件不足把
(3a^2-2ab+2b^2)-(2a^2-b^2-2ab)
=(3+2+2)-(2-1+2)
=7-3
=4
A=1+2+1=4
B=3+4+2=9
3A-B=3*4-9=3