The equation at the right has been incorrectly solved, the answer to this is b = -7
1. You need to multiply the denominator by something that will make the content of the radical be a square—so that when you take the square root, you get something rational. Easiest and best is to multiply by √6. Of course, you must multiply the numerator by the same thing. Then simplify.

2. Identify the squares under the radical and remove them.

Step-by-step explanation:
3 tan 2x - 4 tan 3x = tan² 3x * tan 2x
3 (tan 2x - tan 3x) = tan 3x + tan² 3x * tan 2x
= tan 3x (1 + tan 3x * tan 2x)
3 (tan 2x - tan 3x)/(1 + tan 3x * tan 2x) = tan 3x
3 * (- tan x) = tan 3x
-3tanx = (3 tan x - tan³ x) / (1 - 3 tan² x)
3 - tan² x = - 3 + 9 tan² x
tan x = + √3 /√5 or - √3/√5