Respuesta :

Answer:

^2 on a number means you times the number by itself. You would change 9x^2 to 81x

Step-by-step explanation:

Answer:

x = √11

Step-by-step explanation:

9x² - 12 = 87

=> 9x² = 87 + 12

=> 9x² = 99

=> x² = 99/9

=> x² = 11

=> x = √11

=> x = 3.3 [approximately]