Solve for x.

5x2 - 45 = 0

A.

{3}

B.

{3, - 3}

C.

{9, - 9}

D.

{9}

5x^2-45=0

factor 5 out

5 (x^2-9) = 0

diff 2 perfec squares

5 (x-3) (x+3) = 0

set zero

x-3=0

x=3

x+3=0

x=-3

x=-3 or 3

B

Hi there! 5x²-45=0, add 45 to both sides, 5x²-45+45=0+45=5x²=45. Divide both sides by 5, 5x²/5=45/5, 45/5=9. So, we have x²=9. we have to find the square root of 9. The square root of 9 is 3*3 because 3*3=9. We have two solutions, the first solution is x=3 and the other solution is x=-3. X=3 and x=-3 can be combined and we get {3,-3}. Therefore, your answer is B. {3,-3}