Question

The graphs of the functions $f$ and $g$ are lines, as shown above. What is the value of $f\left(3\right)+g\left(3\right)$?

• A. 1.5
• B. 2
• C. 3
• D. 4
• E. 5.5

Answer 1

The correct option is E 5.5

The line $f\left(x\right)$ going through $(0,0)$ and $(2,1)$

Then $f\left(x\right)=\frac{1-0}{2-0}x+0=\frac{1}{2}x$

$\therefore f\left(3\right)=\frac{1}{2}\times 3=1.5$

And line $g\left(x\right)$ going through point $(0,2)$ and $(3,4)$

Then $g\left(x\right)=\frac{4-2}{3-0}x+2=\frac{2}{3}x+2$

$\therefore g\left(3\right)=\frac{2}{3}\times 3+2=2+2=4$

$\therefore f\left(x\right)+g\left(x\right)=1.5+4=5.5$