Question

7 sin2x - 14 sin x + 2 = -5

Answer 1

Is it \(\sin^2x\)?

Answer 2

@needinghelpyo

Answer 3

can you show me how you got that cause i dont get it at all haha

Answer 4

is ur question
\(7\ sin^2x - 14\ sin x + 2 = -5\)?

Answer 5

yes

Answer 6

\[7{sin}^2x-14sinx+2+5=0\]
\[7{sin}^2x-14sinx+7=0\]
U can factor out 7. Then u will get
\[7({sin}^2x-2sinx+1)=0\]
When u divide by 7 both sides u will get
\[{sin}^2x-2sinx+1=0\]
Nw factorise this and solve for sinx.
Can u do that @needinghelpyo?

Answer 7

or let \(u=sinx\) might be easier with a sub :)

Answer 8

yup u r right @omniscience:)

Answer 9

then would it be sin^2x=1/2

Answer 10

hmm no.
As @omniscience said if u substitute u in place of sinx then u will get
\(u^2-2u+1=0\)
\(u^2-u-u+1=0\)
\(u(u-1)-1(u-1)=0\)
\((u-1)(u-1)=0\)
\((u-1)^2=0\)
\(u-1=0\)
\(u=1\)
\(sinx=1\)
\(x=sin^{-1}1\)

Answer 11

Getting it @needinghelpyo?

Answer 12

yes now i do thank you so much

Answer 13

yw:)