18m^2-1 factor plz!

Question

18m^2-1 factor plz!

anonymous · Answer

$$81m^2-1$$

anonymous · Answer

wait which one, or both

anonymous · Answer

both plz!

anonymous · Answer

if you set them to zero
 just have 
18m^2 -1=0
18m^2 =1
m^2 = 1/18
$$m = \sqrt{1/18}$$

anonymous · Answer

so the same with the other you will have 
$$(m - \sqrt{1/18})^{2}$$
and 
$$(m - \sqrt{1/81})^{2}$$

anonymous · Answer

THANKZ YOUZ!

anonymous · Answer

your welcome

asnaseer · Answer

@Davidjohn - I /think/ your last steps where you factorized the expressions has a mistake in it. I believe you can use the rule $a^2-b^2=(a+b)(a-b)$ to get:$$81m^2-1=9^2m^2-1^2=(9m)^2-1^2=(9m+1)(9m-1)$$

anonymous · Answer

@asnaseer that makes a whole lot more sense!

anonymous · Answer

oh yeah, i generalized that one too much, youre right

anonymous · Answer

but the answer would be right if expanded because it would simplify down and you could multiply them to get the same answer

asnaseer · Answer

glad I could help - and no worries @Davidjohn - we all make mistakes - that's what makes us human :-)

anonymous · Answer

ah except it would be plus or minus then, not just minus minus

asnaseer · Answer

$$(m - \sqrt{1/81})^{2}=m^2-2\sqrt{1/81}+1/81$$

anonymous · Answer

right my bad :) thanks for correcting

anonymous · Answer

Woah... the first thing you showed me was a lot easier to understand...

asnaseer · Answer

:)