Respuesta :

Answer:

b = ±3

Step-by-step explanation:

4b^2-45=-9

Add 45 to each side

4b^2-45+45=-9+45

4b^2 = 36

Divide by 4

4b^2 = 36/4

b^2 =9

Take the square root of each side

sqrt(b^2) = sqrt(9)

b = ±3