有幾條數學題想問！！（緊急）１０點＾＿＾

１a) 2(2-1)<1/7(X-5)
解: 2<1/7(X-5)
X-5>14
X>19

b) x/5-8<-3/5x
解: x/5+3/5x< 8
4x<40
x<10

2)a) 2m(3-n)^2－18m
=2m(9-6n+n^2)－18m
=18m-12mn+2mn^2-18m
=2mn(n-6)

b) -p^3(2x-y)^2+4p^3(x+3y)^2
=-p^3(4x^2-4xy+y^2)+4p^3(x^2+6xy+9y^2)
=-4x^2p^3+4xyp^3-y^2p^3+4x^2p^3+24xyp^3+36y^2p^3
=28xyp^3+35y^2p^3
=7yp^3(4x+5y)

c) a^4(b-3)^2-1
=[a^2(b-3)]^2-1^2
=[a^2(b-3)-1][a^2(b-3)+1]
=(a^2b-3a^2-1)(a^2b-3a^2+1)

d) 81-x^4
=3^4-x^4
=(3^2+x^2)(3^2-x^2)
=(3^2+x^2)(3+x)(3-x)

1a) 2(2-1)<1/7(X-5)
2<(x-5)/7
14
19

1b)可唔可以寫清楚D呀？全中文都得！

2a)2m(3-n)2次－18m
2m+9-6n+n2次-18m
n2次-6n-16m+9

其餘我唔記得，記得再答你！