Question

If $y=3^x$ and 'x' and 'y' are both integers, which of the following is equivalent to $3^{2x}+3^x\times 3?$

• A. $y(y+3)$
• B. $y^2+3$
• C. $3y+3$
• D. $3(y+3)$

Answer 1

The correct option is A $y(y+3)$

$y=3^x$ where x & y both are integers
Now, $3^{2x}+3^x\times 3$ can be rewritten as
$(3^x{)}^2+3^x\times 3$
$=y^2+\left(3y\right)$ (substituting 3x with y)
$=y(y+3)$