Question

Use basic identities to simplify the expression:
cos(x)-cos^3(x)

Answer 1

I have no clue which equations to even look at. I know the answer but not how to get to it.

Answer 2

factorise cos x

Answer 3

I dont know how :/

Answer 4

can you factor this \[a-a^3\]

Answer 5

factor a

Answer 6

no...

Answer 7

I dont understand...its in its lowest form?

Answer 8

\[a-a^3=a(1-a^2)\]

Answer 9

do you understand this

Answer 10

wouldnt it be a(1-a)? cause youre gonna factor?

Answer 11

but it is a^2 cos when we multiply out that it has to give us the original expression
ie a-a^3

Answer 12

but a(1-a)=a-a*a=a-a^2 not a-a^3

Answer 13

I dont follow :(

Answer 14

can you factor this
\[x^3+x^4\]

Answer 15

is that a superscript 3 or 2

Answer 16

x^3(1+x)

Answer 17

yes

Answer 18

ok...

Answer 19

so \[x-x^3\]

Answer 20

factor this

Answer 21

cosx(1-cos^2x)

Answer 22

yes so use this identity
\[\cos ^2x+\sin^2x=1\]...hint take \[\cos ^2x\] to the other side

Answer 23

sin^2x-1=cos^2x?

Answer 24

or do i leave the 1

Answer 25

yes leave the 1

Answer 26

sin^2x=cos^2x+1

Answer 27

cos went to the other side so it is negetive

Answer 28

oh ok
sin^2x=1-cos^2x

Answer 29

yes now go back to your question and look if it is similar to this

Answer 30

i dont understand how you decided to use that identity...

Answer 31

and thats not the right answer..

Answer 32

\[\cos x(\color{red}{1-\cos ^2x})=\cos x \color{red}{\sin^2x}\]
red part from identity

Answer 33

This isnt easy =..erg.. alright

Answer 34

is this the answer or not

Answer 35

no

Answer 36

cos(x)sin^2(x) is the answer

Answer 37

yes thats the one i wrote

Answer 38

i dont see it...

Answer 39

Still need help?

Answer 40

yes

Answer 41

please