Question

The value of 3pi/16 is a solution for 2cos^2(4x) -1 = 0?

Answer 1

I know I have to change it to 2cos^2(4x) = 1

Answer 2

but then I get stuck

Answer 3

there is no need for this
use double angle formula
2cos^2(x)-1 = cos2x

Answer 4

it is given
2cos^2(4x) - 1= 0
cos(8x) = 0
do u follow the last step?

Answer 5

yes I think so

Answer 6

cos of 8 times 3pi/16?

Answer 7

now
cos8x = cos(npi/2) where n= odd numbers
8x = npi/2
in this case n=3
therefore
8x = 3pi/2
x = 3pi/16

Answer 8

did u follow the steps?

Answer 9

yes! thank you so much!! :)

Answer 10

pleasure