Unfortunately your screenshot has cut off the final answer choice, if it says "no solution" you should choose that because these two lines are parallel. Meaning they will never intersect, and the point of intersection is usually the solution.

5 0

3 years ago

HELP ON THIS PROBLEM!! Solve the following 0deg< x< 360deg: cos x= cos 2x

blsea [12.9K]

Answer:

$x=0^\circ,120^\circ,240^\circ,360^\circ$

Step-by-step explanation:

Use identities to set the equation up as a quadratic

$\cos x=\cos 2x;\:0^\circ \leq x \leq 360^\circ\\\\\cos x=2\cos^2 x-1\\\\0=2\cos^2 x-\cos x-1$

Make the substitution u=cos(x) and solve the quadratic

$0=2u^2-u-1\\\\0=(2u+1)(u-1)$

$\displaystyle 0=2u+1\\\\0=2\cos x+1\\\\-1=2\cos x\\\\-\frac{1}{2}=\cos x\\\\120^\circ,240^\circ=x$

$0=u-1\\\\0=\cos x-1\\\\1=\cos x\\\\0^\circ,360^\circ=x$

Hence, $x=0^\circ,120^\circ,240^\circ,360^\circ$

7 0

2 years ago

Rewrite each fraction with a denominator of 10 7/2=? 3/5=?

motikmotik

The answer is 35/10 and 6/10

5 0

2 years ago