中二數學題目 急急急!!!!!

1.
L.H.S.=4(x+3)
=4x+12
=R.H.S.
2.
R.H.S.=2(2x-1)+x-1
=4x-2+x-1
=5x-3
=L.H.S.
3.
L.H.S.=(x+4)^2
=(x+4)(x+4)
=x^2+4x+4x+16
=x^2+8x+16
=R.H.S.
4.
L.H.S.=3(y-4)-2y
=3y-12-2y
=y-12
R.H.S.=2(2y-5)+4
=4y-10+4
=4y-6
L.H.S.≠R.H.S.
5.
3x-5 ≡ Ax-5
3x=Ax A=3
6.
3(2-3y) ≡ 6+Ay
6-9y ≡ 6+Ay
-9y=Ay A=-9
7.
3y(5-2y) ≡ Ay-By^2
15y-6y^2 ≡ Ay-By^2
15y=Ay A=15
-6y=By B=-6
8.
(2x+3)(x-1) ≡ Ax^2-Bx-3
2x^2+x-3 ≡ Ax^2-Bx-3
2x^2=Ax^2 A=2
x=-Bx B=-1
9.3f-9 =3(f-3)
10. x^3+x^2=x^2(x+1)
11.-y-8=-(y+8)
12.c(a+1)-b(a+1)=(a+1)(c-b)
13.4(x-y)+a(y-x)=(x-y)(4-a)
14.ab+bd+ac+cd=b(a+d)+c(a+d)=(a+d)(b+c)
15.7y+14-3x-3x^3=7(y+2)-3x(1+x^2)
16.121-y^2=(11+y)(11-y)
17.x^2+4x+4=(x+2)^2
18.y^2-y-12=(y-4)(y+3)
19.2x^2+7x+3=(2x+1)(x+3)
20.3y^2-2y-5=(3y-5)(y+1)
21.唔知你個「2次n+1」係點，答唔到你