Question

【a²+b²】²-4a²b²

a的4次方×16a²
39×37-13×3的四次方
29×19.99+72×19.99+13×19.99-19.99×14
【m+n】【p-q】-【m+n】【q+p】
a+b=-4，ab=2，求4a²b+4ab²-4a-4b
0.4x-1/0.5-5-x/2≤0.03-0.02x/0.03
9【a+2b】²-4【a-b】²
3x的三次方-12x²y+12xy²8x²-72
【x-y】²-10【y-x】=25
9【a-b】²-16【a+b】²

Answer 1

(1)(a²+b²)²-4a²b²=(a²+b²+2ab)(a²+b²-2ab)
=(a+b)²(a-b)²
=(a²-b²)²
(2)a^4×16a²=16a^6
(3)39×37-13×3^4=39(37-3^3)=39×10=390
(4)29×19.99+72×19.99+13×19.99-19.99×14
=19.99×(29+72+13-14)
=19.99×100
=1999
(5)(m+n)(p-q)-(m+n)(q+p)
=(m+n)(p-q-q-p)
=2p×(m+n)
(6)a+b=-4，ab=2
4a²b+4ab²-4a-4b=4ab(a+b)-4(a+b)
=(a+b)(4ab-4)
=-4×4
= -16
(7)0.4x-1/0.5-5-x/2≤0.03-0.02x/0.03
0.4x-2-(2.5-0.5x)≤0.03-0.02x/0.03
0.1x-4.5≤0.03-2x/3
2.3x≤13.59
x≤5.9
(8) 9(a+2b)²-4(a-b)²
=[3(a+2b)+2(a-b)][3(a+2b)-2(a-b)]
=(5a+4b)(a+8b)
(9)3x^3-12x²y+12xy²8x²-72

(10) (x-y)²-10(y-x)=25
[(x-y)+5]²=50

(11) 9(a-b)²-16(a+b)²
=[3(a-b)+4(a+b)][3(a-b)-4(a+b)]
=(7a+b)(-a-7b)
= -(7a+b)(a+7b)