Respuesta :

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
[tex]28=64-9{ x }^{ 2 }\\ \\ 9{ x }^{ 2 }=64-28\\ \\ 9{ x }^{ 2 }=36[/tex]

[tex]\\ \\ \frac { 1 }{ 9 } \cdot 9{ x }^{ 2 }=\frac { 1 }{ 9 } \cdot 36\\ \\ { x }^{ 2 }=4\\ \\ x=\pm \sqrt { 4 }[/tex]

[tex]\\ \\ \therefore \quad x=\pm 2[/tex]