# What is the standard form of y= 3(2x + 1)(x - 5) ?

Jun 20, 2018

$6 {x}^{2} - 27 x - 15$

#### Explanation:

$3 \textcolor{b l u e}{\left(2 x + 1\right) \left(x - 5\right)}$

Let's ignore the $3$ for now. What I have in blue, we can multiply using the mnemonic FOIL (Firsts, Outsides, Insides, Lasts). This is the order we multiply in.

• First terms: $2 x \cdot x = 2 {x}^{2}$
• Outside terms: $2 x \cdot - 5 = - 10 x$
• Inside terms: $1 \cdot x = x$
• Last terms: $1 \cdot - 5 = - 5$

We get the following:

$2 {x}^{2} - 10 x + x - 5$

Which is equal to

$2 {x}^{2} - 9 x - 5$

Remember, this is what I had in blue. We still have the $3$ on the outside:

$3 \textcolor{b l u e}{\left(2 {x}^{2} - 9 x - 5\right)}$

Distributing the $3$ gives us

$6 {x}^{2} - 27 x - 15$

Hope this helps!