Solve it with steps

Hi,

a² + 4a +x = (a+2)²
=> a² + 4a + x = a² + 2² + (2*a*2) 
=> (a² + 4a + x) - a² - 4a = (a² + 4 + 4a) - a² - 4a  {By subtracting a² and 4a on both sides}
=>  a² + 4a + x - a² - 4a = a² + 4 + 4a - a² - 4a
=> x = 4 {ANS.}

Identities used:
(a+b)² = a² + b² + 2ab 
Method used:
Systematic method to solve the equation. 

Regards.