Question

Factor this completely?
81x^2-25

Answer 1

81 and 25
what do they remind you of ?

Answer 2

numbers? lol

Answer 3

Haha
They are special numbers, think again

Answer 4

they both are composite?

Answer 5

Good. They are more special than that. Try again

Answer 6

they are squared numbers?
other than that i dont know :P

Answer 7

BINGO!

Answer 8

81 = 9^2 and 25 = 5^2

Answer 9

Can we write the given expression as
\[(9x)^2 - (5)^2\]

?

Answer 10

Next recall the identity
\[a^2 - b^2 = (a+b)(a-b)\]

Answer 11

(9x+5)(9x-5)

Answer 12

You got it :-)

Answer 13

thanks to the both of you! <3

Answer 14

Thanks for trying to learn :D

Answer 15

Good job!