9x²- 25
3x(3x) = 9x²
3x(5) = 15x
-5(3x) = -15x
-5(5) = -25
9x² + 15x - 15x - 25
9x² - 25 is your answer
hope this helps
X=9 this is the answer for question 19
Answer:
a = 12m
Step-by-step explanation:
In order to solve this problem we will need to know the Pythagoras theorem that states that in a right angled triangle the square of the hypotenuse (the side opposite to the right angel) is equal to the sum of the squares of the other two sides. This theorem can be written as an equation....

Now we can see that we can easily find the missing value by using this theorem. We just have to substitute the values. And we get the following







I m getting 308.11, there is an additional 0.60 that is added, maybe your source is wrong, or there is a copying error.