Respuesta :

Answer:

x = -4 and x = 4

Step-by-step explanation:

im assuming you meant x^2 + 5 = 21

1. subtract 5 from both sides

x^2 = 21 - 5 = 16

2. isolate x by taking the square root of both sides

sqrt(x^2) = sqrt(16)

x = ±4

Answer:

Step-by-step explanation:

What is the value of x, when c² + 5 = 21?

there is no x, assuming you are looking for c

c^2 + 5 = 21

c^2 = 21 - 5

c^2 = 16

c = √16

c = 4