Given that :-
2a + b = 11
and
ab = 24
Now ,
( 2a + b ) = 11
Squaring both sides , we get
( 2a + b ) ² = 121
=> 4a² + b² + 4ab = 121
putting the value of ab here , we get
=> 4a² + b² + 4 * 24 = 121
=> 4a² + b² + 96 = 121
=> 4a² + b² = 121 - 96
=> 4a² + b² = 25