There is a rectangle with a width of 5x and a length of x + 4. How do you find the area of the rectangle?

$5 {x}^{2} + 20 x$

Explanation:

The area of a rectangle is given by the product of its width by its length, therefore, $5 x \cdot \left(x + 4\right) = 5 x \cdot x + 5 x \cdot 4 = 5 {x}^{4} + 20 x$//

May 23, 2016

$\text{area } = 5 {x}^{2} + 20 x$

Explanation:

area is width multiplied by length

Length given as $x + 4$
Width given as $5 x$

Let area be $a$
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So area is width multiplied by length$\text{ } \to a = 5 x \times \left(x + 4\right)$

Normally written as $a = \textcolor{b l u e}{5 x} \textcolor{b r o w n}{\left(x + 4\right)}$

We multiply everything inside the bracket by $\textcolor{b l u e}{5 x}$

So we have:

a=color(brown)((color(blue)(5x xx)x )+(color(blue)(5x xx)4)

$a = 5 {x}^{2} + 20 x$

$\textcolor{red}{\text{As we do not know the value of " x " we can not take this any further}}$