how do I find the value of x so f(x)=7

The value of [tex]x[/tex] so [tex]f(x) = 7[/tex] is 5.
According to the figure, we have a linear function and linear functions have the same slope for all value of [tex]x[/tex], we can determine the value of [tex]f(x)[/tex] for [tex]x = 7[/tex] by means of the equation for the secant line:
[tex]\frac{y_{B}-y_{A}}{x_{B}-x_{A}} = \frac{y_{C}-y_{A}}{x_{C}-x_{A}}[/tex] (1)
Where:
[tex](x_{A}, y_{A})[/tex], [tex](x_{B}, y_{B})[/tex] - Known points.
[tex](x_{C}, y_{C})[/tex] - Expected point.
If we know that [tex](x_{A},y_{A}) = (2, 0)[/tex], [tex](x_{B}, y_{B}) = (5, 7)[/tex] and [tex]y_{C} = 7[/tex], then the value of [tex]x_{C}[/tex] is:
[tex]x_{C}-x_{A} = \frac{y_{C}-y_{A}}{y_{B}-y_{A}}\cdot (x_{B}-x_{A})[/tex]
[tex]x_{C} = x_{A} + \frac{y_{C}-y_{A}}{y_{B}-y_{A}} \cdot (x_{B}-x_{A})[/tex]
[tex]x_{C} = 2 + \frac{7-0}{7-0}\cdot (5-2)[/tex]
[tex]x_{C} = 2 + (5-2)[/tex]
[tex]x_{C} = 2 + 3[/tex]
[tex]x_{C} = 5[/tex]
The value of [tex]x[/tex] so [tex]f(x) = 7[/tex] is 5.
We kindly invite to check this question on extrapolations: https://brainly.com/question/18768845