The answer is

first you must multiply or use the FOIL method (First, Outer, Inner, Last)
First you multiply the first terms

this gives you 3x^2, then you multiple the outer terms

this gives you -21x, then you multiply the inner terms

that gives you 2x, finally you multiply the last terms

that gives you 14, now you combine like terms

now you put all the terms together and end up with your solution
If their perimeters are equal, we can add up all the side lengths of each triangle, and set the perimeters equal to each other to find the value of x that satisfies the equation:
x - 2 + x + 3x + 1 = 2x - 5 + x + 4 + 6x - 7
Combine like terms:
5x - 1 = 9x - 8
And finally, solve for x:
7 = 4x
x = 
Therefore, x is equal to
.
<em>Hope this helps! :)</em>
Answer:
x=5
Step-by-step explanation:
x^2+25-10x = x^2-25
-x^2 -x^2
25-10x = -25
-25 -25
-10x = -50
x=5
lets check
(5-5)^2 = 5^2-25
0^2 = 25-25
0 = 0