# How do you find the value of x so that the function n(x) = 7x +4 has the given value 39?

Apr 19, 2018

$x = 5$

#### Explanation:

the function has a value of 39 when n(x)=39, therefore we can substitute 39 instead of n(x) and solve for x

$n \left(x\right) = 7 x + 4$
$39 = 7 x + 4$
$7 x + 4 = 39$
$7 x + 4 - 4 = 39 - 4$
$7 x = 39 - 4$
$7 x = 35$
$\frac{7 x}{7} = \frac{35}{7}$
$x = 5$

you can check your answer by plugging the value of $x$ back into the original function and seeing if the n(x) value is 39

$n \left(x\right) = 7 x + 4$
$n \left(5\right) = 7 \left(5\right) + 4$
$n \left(5\right) = 35 + 4$
$n \left(5\right) = 39$

$\therefore$ the answer is correct