NOTE: This is a multi$-$part question. Once an answer is submitted, you will be unable to return to this part.

Let P$($n$)$ be the statement that $112$

$+123$

$+...+1$n$($n$+1)$

$=$ n$($n$+1)$

$.$

Ch $05$ Sec $1$ Ex $10($b$)3$rd $-$ n$/($n $+1)-$ Identifying P$($k $+1)$

Identify the statement P$($k $+1).$

Multiple Choice

$112+123+...+1$k$($k$+1)+1($k$+1)($k$1)=$k$+1$k$+2$

is true for a specific k $>0.$

$112+123+...+1$k$($k$+1)+1($k$+1)($k$2)=$k$+1$k$+2$

is true for a specific k $<0.$

$112+123+...+1$k$($k$+1)+1($k$1)($k$+2)=$k$+1$k$+2$

is true for a specific k $<0.$

$112+123+...+1$k$($k$+1)+1($k$+1)($k$+2)=$k$+1$k$+2$

is true for a specific k $>0.$