Who knows how to do this 8 cos x+3=0 ? ?

You want to find the measure of angle x.  Rearrange the given 8 cos x+3=0 as 8 cos x= -3, or cos x = -3 / 8, or cos x = -0.375.  

Use the arccos function (inverse cosine) to find the value of x in radians and in degrees.

Since the cosine function is negative only in Quadrants II and III, focus on the following possible ranges:  Quadrant II:  90 < x < 180 and
Quadrant III:  180 < x < 270.

Example:  using my calculator to obtain the inverse cosine of -0.375, I got x = 1.96 radians.  Convert this into degrees if desired.  Draw a ray showing this angle.  Reflect this ray across the horiz. axis to obtain the angle in Q III.

Hello!

the answer is:

the answer is:

why?

to solve the problem, we need to remember the quotient of power property, it's defined by the following relation:

if we have a quotienf of powers that have the same base, we need to keep the same base and subtract the exponent of the denominator power to the exponent of the numerator power.

so, we are given the expression:

then, calculating we have:

hence, the answer is:

have a nice day!