Question

factor 4z^2-81

Answer 1

hint : 4 = 2^2
81= 9^2

Answer 2

and \(\large a^2-b^2=(a+b)(a-b)\)

Answer 3

what?

Answer 4

did you get this ?
\(\large 4z^2-81= (2z)^2-9^2\)

Answer 5

no?

Answer 6

ok, so did you know 4 = 2^2 ?

Answer 7

no...can u please help me from the start?

Answer 8

thats the start!
1) write 4 as 2^2
2) write 81 as 9^2
then just apply the difference of square formula i mentioned, and you are done.

Answer 9

and i am really surprised, how can one not know 2^2=..

Answer 10

i mean... of course i knew that but i was just asking for an entire walkthrough considering i'm studying for 3 tests at once -_- but thankss

Answer 11

4z^2-81
(2z-9)(2z+9)

check: 2z(2z)+18z-18z-(9)(9)

cancel +18z-18z

and u'll get the answer like this 4z^2-81

Answer 12

ty :)