Answer:
The answer is 96 when X= 8 
Explanation:
We have given that : 
AE= 
 and CE=
 
where AE and CE are the diagonals of the paralleogram
The diagonals of parallelogram bisect each other therefore, 
 

⇒ 

factors are (x+2)(x-8)=0
setting to each factor 0 the value of x= -2 or x= 8 
therefore, two values of AC is 
X= -2 ,AC= 2(
)=2(-12)=-24
X= 8  ,AC= 2(
)=2(48)=96 
The answer is 96 when X= 8