Question

If $4x^2+a+1$ has a remainder $0$ when divided by $x+1$, then what will be $a$?

• A. $0$
• B. $2$
• C. $-5$
• D. $5$

Answer 1

The correct option is C $-5$

Replace $x$ as $-1$ in the expression:
$4x^2+a+1$
$=$ $4(-1{)}^2+a+1$
$=4+a+1$
$=5+a$
So, the remainder is $5+a$, Now substitute the value of remainder, we know that is $0$.
$5+a=0$
$a=-5$