Question

If a function $f$ is linear with $f\left(0\right)=5$ and $f\left(2\right)=9$ then find $f\left(9\right)$

• A. 23
• B. 25
• C. 26
• D. none of these

Answer 1

Answer: (A)

23

$f$ is a linear function

So Let $f=ax+b$

$f\left(0\right)=a\left(0\right)+b=5⟹b=5\cdots \left(1\right)f\left(2\right)=9a\left(2\right)+5=9⟹a=2f\left(x\right)=2x+5f\left(9\right)=2\left(9\right)+518+5=23$