Question

PLZ HELP ME BY THE END OF THE DAY
Lisa solved 3x2 + 1 = 28 as shown. 3x2 + 1 = 28 3x2 = 27 x2 = 9 She concluded that the solutions to this quadratic equation are x = -9 or x = 9. What are the correct solutions to this quadratic and how did you arrive at your answer?

Answer 1

$3x^{2} +1=28$

Step 1 : subtract 1 from both sides

$3x^{2} =27$

Step 2 : Divide both sides by 3

$\frac{\frac{3x^{2} }{3} }{\frac{27}{3} }$

$x^{2} = 9$

Step 3 : Find the square root of 9

$\sqrt{9} = 3$

x= (-3,3)

remember negative × negative = positive