Answer:
2(2r + 1)(2r - 5)
Step-by-step explanation:
Given
8r² - 16r - 10 ← factor out 2 from each term
= 2(4r² - 8r - 5)
To factorise the quadratic
Consider the factors of the product of the coefficient of the r² term and the constant term which sum to give the coefficient of the r- term.
product = 4 × - 5 = - 20 and sum = - 8
The factors are + 2 and - 10
Use these factors to split the r- term
4r² + 2r - 10r - 5 ( factor the first/second and third/fourth terms )
= 2r(2r + 1) - 5(2r + 1) ← factor out (2r + 1) from each term
= (2r + 1)(2r - 5), so
4r² - 8r - 5 = (2r + 1)(2r - 5) and
8r² - 16r - 10 = 2(2r + 1)(2r - 5) ← in factored form
Since you are solving for a, you want to have a on one side of the equation and the other terms on another side of the equation. It would be easiest to have all the terms with a on the left side of the equation, so that is what we will do.
Subtract 9a from both sides to get a on the left side of the equation.
5 + 5a = -5
Subtract 5 from both sides of the equation to isolate the term with a.
5a = -10
Divide both sides of the equation by 5 to solve for a.
a = -2
Answer:
1:144 ft²
Step-by-step explanation:
9 : 1296
1 : x
9x = 1296
x = 1296/9
x = 144
Scale factor = 1:144