Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Continuity and Differentiability

Question:
Find the values of $a$ and $b$ such that the function $f$ defined by $f(x)=\begin{cases} 5& \text{if}\hspace{.2cm} x \leq 2\\ ax+b& \text{if}\hspace{.2cm} 2< x<10\\ 21,& \text{if}\hspace{.2cm} x\geq 10\\ \end{cases}$ is a continuous function.
Options:
$a=3,b=5$
$a=2,b=1$
$a=1,b=2$
$a=4,b=3$
Correct Answer:
$a=2,b=1$
Explanation:
From the continuity at the point $x=2$ we get $2a+b=5$ and from the continuity at the point $x=10$ we get $10a+b=21$. Solving these two equations we get $a=2,b=1$