Thread: New problem: 2cos^2 2x = cos2x + 1

This time with a harder one. All the hints are really appreciated. Been banging my head to wall few days with this one...

So, here it is:



Thanks!

--
When you think you know it, you don't!

Originally Posted by thex10

This time with a harder one. All the hints are really appreciated. Been banging my head to wall few days with this one...

So, here it is:



Thanks!

--
When you think you know it, you don't!

Note that you can rewrite it as . Also observe that if you make a substitution, say , the equation becomes quadratic in form: .

Solve this quadratic equation for u, and then backsubstitute to find x.

Can you take it from here?

Originally Posted by thex10

This time with a harder one. All the hints are really appreciated. Been banging my head to wall few days with this one...

So, here it is:



Thanks!

--
When you think you know it, you don't!

What are you suppose to be doin? verifying the identity or findin the solutions?

Originally Posted by purplec16

What are you suppose to be doin? verifying the identity or findin the solutions?

the equation is conditional ... it's not an identity.

Originally Posted by Chris L T521

Note that you can rewrite it as . Also observe that if you make a substitution, say , the equation becomes quadratic in form: .

Solve this quadratic equation for u, and then backsubstitute to find x.

Can you take it from here?

Thank you! Now I understood it

--
When you think you know it, you don't!