Use the geometric mean for right triangles here. Like this

. Cross multiply to get

, and

. That simplifies down to

. Pull out the 9 as a perfect square of 3 and you're left with

, first choice above.
Answer:
40x^3 -10x
Step-by-step explanation:
Used math-way to solve this! I'm sorry if wrong, x
Answer:
What are the coordinates for point C?
Answer:
When we simplify the problem we get 33/8
DE + EF = DF
x - 2 + 6x + 4 = 8x - 2
7x + 2 = 8x - 2
2 + 2 = 8x - 7x
4 = x <===