The answer is 6 btw it’s wrong!
Answer: 
Step-by-step explanation:
Equilateral triangle has equal sides, let the side be
, then the perimeter is 
Therefore:



To find the altitude , we will apply Pythagoras theorem , that is

Therefore:



take the square root of both sides

In the equation you have to replace all x's with -1
f (-1) = (-1)^2 - 8(-1) +5
f (-1) = 1 + 8 + 5
f (-1) = 14
the f(-1) stand for the function of -1. it is also equivalent to y
Answer:
25x^2 -1
Step-by-step explanation:
If you multiply parentheses:
(5x*5x) + (5x*-1) + (1*5x) + (1*-1)
25x^2 - 5x + 5x -1
25x^2 -1
A simpler way is to memorize this formula
(Square1 - square2)= (sqrt of square1- sqrt of square2)*(sqrt of square1 + sqrt of sqaure2)