Question

what is the simplified form of x^4-81/x+3

Answer 1

@Michele_Laino do u think u can help me by any chance?

Answer 2

x^4 - 81 can be regarded as the difference of 2 squares
(x^2)^2 - 9^2
- can you factor that?
- remember that a^2 - b^2 = (a + b)(a - b)

Answer 3

how do i factor that? @welshfella

Answer 4

@welshfella

Answer 5

relace a by x^2 and b by 9 and see what you get

Answer 6

can u put that in a formula for me then i will solve it best i can

Answer 7

a^2 - b^2 = ( a + b)( a - b)

just replace a by x^2 and b by 9

Answer 8

so (x^2)^2-81?

Answer 9

(x^2)^2 - 9^2 = ?

Answer 10

(x^2+9)(x^2-9) ?? @welshfella

Answer 11

right
now do you think any os those 2 factors will factor any further?

Answer 12

one of them will

Answer 13

we have another 'difference of 2 squares'

Answer 14

uhhhh idrk could u explain that more?

Answer 15

x^2 - 9 = ?

Answer 16

take the 2 square roots, giving:-

x^2 - 9 = ( x - 3)(x + 3)

Answer 17

right? - similar thing to the first step

Answer 18

have a good look at it I think you'll see it
i gotta go right now

Answer 19

x^3-3x^2+9x-27 ?? @welshfella

Answer 20

sorry must go

Answer 21

:( was i right tho? @welshfella

Answer 22

the x +3 cancesl out

x^4 - 81 = (x^2 + 9)(x + 3)(x - 3)
-------- -------------------- = (x^2 + 9(x - 3)
x + 3 (x + 3)

Answer 23

yes

Answer 24

so i was right? @welshfella

Answer 25

yup

Answer 26

thanks!

Answer 27

yw