How do you find the value of f(1/2), if f(x)=3x-4?

2 Answers
May 3, 2017

See the solution process below:

Explanation:

Substitute $\textcolor{red}{\frac{1}{2}}$ for each occurrence of $\textcolor{red}{x}$ in the function $f \left(x\right)$ and calculate the result:

$f \left(\textcolor{red}{x}\right) = 3 \textcolor{red}{x} - 4$ becomes:

$f \left(\textcolor{red}{\frac{1}{2}}\right) = \left(3 \times \textcolor{red}{\frac{1}{2}}\right) - 4$

$f \left(\textcolor{red}{\frac{1}{2}}\right) = \frac{3}{2} - 4$

$f \left(\textcolor{red}{\frac{1}{2}}\right) = \frac{3}{2} - \left(\frac{2}{2} \times 4\right)$

$f \left(\textcolor{red}{\frac{1}{2}}\right) = \frac{3}{2} - \frac{8}{2}$

$f \left(\textcolor{red}{\frac{1}{2}}\right) = \frac{3 - 8}{2}$

$f \left(\textcolor{red}{\frac{1}{2}}\right) = - \frac{5}{2}$

May 3, 2017

$f \left(\frac{1}{2}\right) = - \frac{5}{2}$

Explanation:

Sub $x = \frac{1}{2}$ into the function,

$f \left(\frac{1}{2}\right) = 3 \left(\frac{1}{2}\right) - 4$

$f \left(\frac{1}{2}\right) = \frac{3}{2} - 4$

$f \left(\frac{1}{2}\right) = \frac{3}{2} - 4$

$f \left(\frac{1}{2}\right) = - \frac{5}{2}$ or $- 2.5$