Question

If $\underset{x\to -1}{lim}(a{x}^2+bx+c)=1$ where $a,b,c\in R,$ then which of the following is true

• A. $a-b+c=1$
• B. $a+b+c=1$
• C. $a+b-c=1$
• D. $a+b+c+1=0$

Answer 1

The correct option is A $a-b+c=1$

$\underset{x\to -1}{lim}(a{x}^2+bx+c)=1$
To evaluate the limit of a polynomial function, we use direct substitution.
$\Rightarrow a(-1{)}^2+b(-1)+c=1$
$\Rightarrow a-b+c=1$