數學(簡單)　　１０！

1) a^2+6a+9 = ?
a^2+6a = -9
a(^2+6) = -9
a = -9/(^2+6)

2) 81-(2x-3y)^2 = ?
(2x-3y)^2 = 81
2x-3y = 81/^2

3) (2x-y)^2-x^2 = ?
(2x-y)^2 = x^2
2x-y = x^2/^2
2x-y = x
2x-x = y
1x = y

其實，呢d係咩數呀......究竟係每條要求咩代數都唔講清楚...
我都唔明有咩簡單...
我盡量俾d step你...
仲有想問...^..這個符號係咪要跟住前面果個家...
可以既話就補充下啦...good luck!

6a coeficient is 6.
6/2=3

so 1) (a+3)^2
6a can be used to determine the base of the final answer.


2) (9+2x-3y)(9-2x+3y)

3) (2x-y+x)(2x-y-x)
=(3x-y)(x-y)

OR

(2x-y)^2-x^2
=4x^2-4xy+y^2-x^2
=3x^2-4xy+y^2
=(3x-y)(x-y)

(The first method should be better.)