Question

How can I factor the following equation:
28n^4+16n^3-80n^2

Answer 1

first factor n^2

Answer 2

then factor 4

Answer 3

4n^2 (7n^2-4n-20)

Answer 4

so I have to distribute?...the 4n^2 to the numbers in the parenthesis?

Answer 5

no, factoring is the opposite of distributing

Answer 6

ok

Answer 7

the next step is to see if you can factor 7n^2-4n-20

Answer 8

oh...ok

Answer 9

What if you can't?

Answer 10

you don't pass ?

Answer 11

that 7 in front of the n^2 makes factoring this a pain.

one way to factor it is first multiply 7*20 (the 7 times the last number, ignoring the sign)
you get 140

now we need to list pairs of numbers that multiply to give 140
1,140
2,70
4,35
5,28
7,20
10,14

and look for a pair with *opposite signs* add up to -4 (the middle number in your problem)

Answer 12

the last pair

Answer 13

the last pair work, if we use +10 and -14

we know the 7 in front of n^2 means we will have
(7n )(n )

we know we need a -14
to get a -14 (using that 7) is put -2 in the 2nd parens

Answer 14

yes exactly

Answer 15

that leaves a +10 for the (7n )

Answer 16

(7n+10)(n-2)

I would check this answer, by multiplying it out:
7n*n = 7n^2
7n* -2= -14n
10*n= 10n
10*-2 = -20
add up

7n^2 -14n + 10n -20
simplify
7n^2 -4n -20

Answer 17

Alright.

Answer 18

Ty :D phi