=1 Formula used: loga=b⇒a=10b Calculation: ⇒log10(100001−4x)=5−x ⇒100001−4x=105−x ⇒100001−4x=105−x Check all the options: x=0 ⇒100001−40=105−0 ⇒100001−1=100000 x=0 satisfies the condition. x=1 ⇒100001−41=105−1 ⇒100001−4=10000 ⇒99997≠10000 x=1 does not satisfy the condition. x=10 ⇒100001−410=105−10 ⇒100001−410≠10−5 x=10 does not satisfy the condition.
