Question

How do I solve 28=64-9x^2 using square roots?

Answer 1

1. Subtract 64 from each side of the equation

-36=-9x^2

2. Separate -9 from x^2 by dividing -9 from each side. The negatives will cancel leaving a positive on the left.

4=x^2

3. Last, take the square root of each side in order to get rid of the exponent.

2=x

4. Quick Check

28=64-9(2)^2
28=64-9(4)
28=64-36
28=28

Answer 2

`28=64-9{ x }^( 2 )\\ \\ 9{ x }^( 2 )=64-28\\ \\ 9{ x }^( 2 )=36`


`\\ \\ \frac { 1 }{ 9 } \cdot 9{ x }^( 2 )=\frac { 1 }{ 9 } \cdot 36\\ \\ { x }^( 2 )=4\\ \\ x=\pm \sqrt { 4 }`


`\\ \\ \therefore \quad x=\pm 2`