好吃花魁怜怜书包网:数学题(急)

(1)7x^2-63
=7(x^2-9)
=7(x+3)(x-3)
(2)a^3-a
=a(a^2-1)
=a(a+1)(a-1)
(3)3a^2-3b^2
=3(a^2-b^2)
=3(a+b)(a-b)
(4)y^2-9(x+y)^2
=[y+3(x+y)][y-3(x+y)]
=(3x+4y)(-3x-2y)
(5)a(x-y)-b(y-x)+c(x-y)
=a(x-y)+b(x-y)+c(x-y)
=(a+b+c)(x-y)
(6)x(m+n)-y(n+m)+(m+n)
=x(m+n)-y(m+n)+(m+n)
=(x-y+1)(m+n)
(7)(x+y)^2-16(x-y)^2
=[(x+y)+4(x-y)][(x+y)-4(x-y)]
=(5x-3y)(-3x+5y)
(8)a^2(a-b)^2-b^2(a+b)^2
=[a(a-b)+b(a+b)][a(a-b)-b(a+b)]
=(a^2+b^2)(a^2-2ab-b^2)
(9)(x+y+z)^2-(x-y-z)^2
=[(x+y+z)+(x-y-z)][(x+y+z)-(x-y-z)]
=4x(y+z)
(10)(x+y)^2-14(x+y)+49
=[(x+y)-7]^2
=(x+y-7)^2
(1)a^2b^2-0.01
=(ab+0.1)(ab-0.1)
(2)x^2y-2xy^2+y^3
=y(x^2-2xy+y^2)
=y(x-y)^2
(3)16-(2a+3b)^2
=[4+(2a+3b)][4-(2a+3b)]
=(2a+3b+4)(-2a-3b+4)
(4)(a^2+4)^2-16a^2
=[(a^2+4)+4a][(a^2+4)-4a]
=(a+2)^2(a-2)^2
(5)x^2-xy+1/4y^2
=(x-1/2y)^2
(6)a^2x^2+16ax+64
=(ax+8)^2
(7)a^4-8a^2b^2+16b^4
=(a^2-4b^2)^2
=(a+2b)^2(a-2b)^2
(8)9+6(a+b)+(a+b)^2
=[3+(a+b)]^2
=(a+b+3)^2