Question

The roots of the equation $3^{2x}-{10.3}^x+9=0$ are

• A. 1,2
• B. 0,2
• C. 0,1
• D. 1,3

Answer 1

The correct option is B

0,2

Given equation is $3^{2x}-{10.3}^x+9=0$ can be written as

Let a = $3^x$, then it reduces to the equation

$a^2-10a+9=0$ ⇒ (a - 9)(a - 1) = 0 ⇒ a = 9, 1

Now a = $3^x$ ⇒ 9 = $3^x$ ⇒ $3^2$ = $3^x$ ⇒ x = 2

and 1 = $3^x$ ⇒ $3^0$ = $3^x$ ⇒ x = 0

Hence roots are 0, 2