Posted by **emily** on Tuesday, May 18, 2010 at 6:56am.

how to solve y= 3cos2x + 5

pls help me

- math -
**drwls**, Tuesday, May 18, 2010 at 8:21am
Is that really cos(2x) or do you mean cos^2 x?

I will assume that you really do mean cos(2x). In that case

cos(2x) = cos^2 x - sin^2 x

= 2 cos^2 x -1

y = 6 cos^2x -3 + 5 = 6 cos^2 x - 2

cos^2 x = (y+2)/6

cos x = sqrt[(y+2)/6)]

You can use that to solve for x, if that is what the question is all about.

You cannot solve a single equation for both x and y.

## Answer This Question

## Related Questions

- Math - Can u pls pls pls solve this algebraic expression?? I cant solve it ...
- Mathematics - Hi there, Can someone help me with the question: "Prove that the ...
- trig - Solve for all real values of x 3cos2x - 5cosx = 1
- Trig - use a graphing utility to solve each equation, rounded to 2 decimal ...
- Maths - trig - Solve 3cos2x - 7cosx = 0, when 0<=x<=360 And also, find the...
- Math - Pls help .[1] Solve the eguation 4*=28. [2] change 1/20 to decimal [3] ...
- Trigonometry - Solve for x in the interval 0<=x<360: 1. 2sin2x+cosx =0 2. ...
- (pls help) algebra - 4x+y-32=1, 6x-y-4z=7, 10x+2y-6z=5 pls show me how to solve ...
- science help - How can you describe the location of hafnium (Hf, atomic number ...
- math(urgent) - $1000 was invested for two years at 10% simple interest ....

More Related Questions