第1个回答 2013-11-16
x五次方y四次方+x四次方y五次方
=x四次方y四次方(x+y)
=(xy)四次方(x+y)
=1的四次方×4
=4
(a-b)²-16(a+b)²
=(a-b)²-(4a+4b)²
=(a-b+4a+4b)(a-b-4a-4b)
= -(5a+3b)(3a+5b)
x³y+xy³+2x²y²
=xy(x²+y²+2xy)
=xy(x+y)²
=(3/4)×2²
=3
第2个回答 2013-11-16
解
x+y=4
xy=1
x^5y^4+x^4y^5
=(xy)^4(x+y)
=1×4
=4
(a-b)²-16(a+b)²是这个吗
=[(a-b)-4(a+b)][(a-b)+4(a+b)]
=(-3a-5b)(5a+3b)
=-(3a+5b)(5a+3b)
x³y+xy³+2x²y²
=xy(x²+2xy+y²)
=xy(x+y)²
=3/4×4
=3
第3个回答 2013-11-16
x^5y^4+x^4y^5
=x^4y^4(x+y)=1×4=4
(2)(a-b)²-16(a+b)²
=[(a-b)+4(a+b)][(a-b)-4(a+b)]
=-(5a+3b)(3a+5b)
(3)x³y+xy³+2x²y²
=xy(x²+y²+2xy)
=xy(x+y)²
∵x+y=2,xy=3/4
∴上式=3/4×2²=3