Question

If $X=\{4^n-3n-1:n\in N\}$ and $Y=\{9(n-1):n\in N\}$, then $X\cap Y=$

• A. X
• B. Y
• C. $\varphi$
• D. {0}

Answer 1

Answer: (A)

We have,
$X=\left\{4^n-3n-1:n\in N\right\}$
$=\{0,9,54,\dots ...\}$
$Y=\{9(n-1):n\in N\}$
$=\{0,9,18,27,36,45,54,\dots \dots \}$
$\therefore X\cap Y=X$