Question

If $3^x+3^{x-2}=30$ then value of x is:
(A) 3
(B) 1
(C) -1
(D) -3

Answer 1

here is the answer....

Answer 2

Answer:

(A) 3

Step-by-step explanation:

$3^x+3^{x-2}=30$

$3^x+3^{x}(3^{-2})=30$

$3^x(1 +3^{-2})=30$

$3^x(1 +\dfrac{1}{3^2} )=30$

$3^x(1 +\dfrac{1}{9} )=30$

$3^x(\dfrac{10}{9} )=30$

$3^x=30 \div \dfrac{10}{9}$

$3^x=30 \times \dfrac{9}{10}$

$3^x=27$

$3^x=3^3$

∴ x = 3

Answer: (A) 3