Wednesday

July 30, 2014

July 30, 2014

Posted by **Joanie** on Tuesday, January 20, 2009 at 6:13pm.

- Math -
**Reiny**, Tuesday, January 20, 2009 at 6:47pmDid you mean

4sin^2x + 4√2cosx -6 = 0 ?

if so then

4(1-cos^2x) + 4√2cosx - 6 = 0

4 - cos^2x + 4√2cosx - 6 = 0

2cos^2x + 2√2cosx + 1 = 0

let cosx = y

then y = (-2√2 ± √(8 - 4(2)(1))/4

y = -√2/2

then cosx = -√2/2

we know that cos 45 = √2/2

and x must be in the II or III quadrant, so

x = 180-45 = 135 degrees or

x = 180+45 = 225 degrees

in radians that would be 3pi/4 or 5pi/4 radians

general solution

x = 135 + 360k, 225 + 360k, k an integer

or

x = 3pi/4 + 2kpi, 5pi/4 + 2kpi

- Math -
**Joanie**, Tuesday, January 20, 2009 at 8:34pmThank you for helping me with this problem.

Joanie

**Related Questions**

Advanced Math - Solve 4sin^2 x + 4sqrt(2) cos x-6 = 0 for all real values of x. ...

Pre Cal - Solve 4sin^2 x + 4sqrt(2) cos x-6 = 0 for all real values of x. My ...

Pre Cal. - So I posted these...but no one answered them. Are they right? Solve ...

calculus - write the expression in the form bi, where b is the real number ...

Algebra2 - Simplify: 1.SquareRoot(-144) 2.SquareRoot(-64x^4) 3.SquareRoot(-13)*...

Algebra - I need some help figuring these. Compute each product and simplify ...

Algebra - I need some help figuring these. Compute each product and simplify the...

maths - q1) 2cos2x is f(x) -square root3 is g(x) solve f(x)-g(x)=0 to get points...

Pre-calculus - solve 4 sin^2x + 4 sqrt 2 cos x-6=0 for all real values of x. ...

math - solve the equation 1. squareroot of 2x+1+4=3 2.x= squareroot of 12-x 3....