isi-entrance 2015 Q5

isi-entrance · India · UGB 4 marks Laws of Logarithms Solve a Logarithmic Equation

If $\log _ { 10 } x = 10 ^ { \log _ { 100 } 4 }$, then $x$ equals
(a) $4 ^ { 10 }$
(b) 100
(c) $\log _ { 10 } 4$
(d) none of the above.

(b) Let $y = \log _ { 10 } x$. Then $\log _ { 10 } y = \log _ { 100 } 4$. Hence $y = 2$.

If $\log _ { 10 } x = 10 ^ { \log _ { 100 } 4 }$, then $x$ equals\\
(a) $4 ^ { 10 }$\\
(b) 100\\
(c) $\log _ { 10 } 4$\\
(d) none of the above.