If A=1    0    25    1    x1    1    1 is a singular matrix, then x is equal to

As A is a singular matrix,|A|=0⇒10051x−1011−1=0                                                 [using C3→C3−2C1]⇒ 1x−101−1=0 ⇒ −1∣−x+10=0⇒ x=9