Answer:
(4x - 3)(3x² + 1)
Step-by-step explanation:
Given
12x³ - 9x² + 4x - 3 ( factor the first/second and third/fourth terms )
= 3x²(4x - 3) + 1(4x - 3) ← factor out (4x - 3) from each term
= (4x - 3)(3x² + 1) ← in factored form
As the exercise says, the triangles are similar. So, we can set up proportions between correspondent sides.
In order to solve for x we can set up the proportion between the horizontal and vertical sides:

Solving this proportion for x implies 
Now you can solve for m and p using the pythagorean theorem, because both triangles are right:

Then, we know that the hypothenuse of the big triangle is m+p, so we have

which implies
