What are the solutions of the equation? x^2+4x=21 a. 23, -27 b. 3, -7 c. -3, 7 d. 4.8, -4.8

Option (b) is correct.

The solution of the quadratic equation  is -7 and 3

Step-by-step explanation:

Consider the given quadratic equation

This can be rewritten as,

We can solve the quadratic equation using middle term splitting method,

4x can be written as 7x-3x , we get,

Taking terms common, we get,

Thus,

Thus, we get (x-3)= 0 or (x+7)= 0  

this gives x = 3 or x = -7

Thus, the solution of the quadratic equation  is -7 and 3