Question

How do you multiply `(5y-2)(5y+2)`?

Answer 1

25y^2-4#.

Explanation:

Using the Identity `(a+b)(a-b)=a^2-b^2`.

`:. (5y-2)(5y+2)=(5y)^2-2^2=25y^2-4`.

Answer 2

`25y^2-4`

Explanation:

We must ensure that each term in the 2nd bracket is multiplied by each term in the 1st bracket. This can be achieved as follows.

`(color(red)(5y-2))(5y+2)=color(red)(5y)(5y+2)color(red)(-2)(5y+2)`

now distribute each pair of brackets and collect 'like terms'

`=25y^2+cancel(10y)-cancel(10y)-4=25y^2-4`