Question

Please help ASAP! Will give BRAINLIEST! Please read the question THEN answer correctly! No guessing.

Answer 1

Answer:

A. $\frac{9}{2}$

F. $- \frac{9}{2}$

Step-by-step explanation:

$4 {x}^{2} - 81 = 0 \\ {(2x)}^{2} - {(9)}^{2} = 0 \\ (2x + 9)(2x - 9) = 0 \\ 2x + 9 = 0 \: \: or \: \: 2x - 9 = 0 \\ x = - \frac{9}{2} \: \: or \: \: x = \frac{9}{2}$

Answer 2

Answer:

A and F

Step-by-step explanation:

In an equation our aim is to find the value of what we are looking for as well as keeping the equation balanced. For example if we took away 81 only from one side then the equation would change so it's an important rule to keep in mind when solving equations, that you need to keep both sides of the equation the same.

4x² - 81 = 0

→ Add 81 to both sides to isolate 4x²

4x² = 81

→ Divide both sides by 4 to isolate x²

x² = 20.25

→ Square root both sides to isolate x

x = 4.5

Since this is a quadratic, the solution can be negative so the answer is -4.5 and 4.5