# How do you simplify -3(4x-1)+9x+8x?

Feb 28, 2016

Just in case it is needed; I have explained about multiplying the bracket.

#### Explanation:

Further explanation about how to handle $- 3 \left(4 x - 1\right)$

Consider as an example $2 \times a \to 2 a$

This means we have two of $a$

That is $a + a$

So $3 a$ means we have three of $a$. That is $a + a + a$

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Ok! carry that thought into$\text{ } - 3 \left(4 x - 1\right)$

for a moment forget that this is multiplied by negative 3. Just think it as being multiplied by positive 3

So$\text{ "3(4x-1)" is the same as } 3 \times \left(4 x - 1\right)$

Which is the same as$\text{ } \left(4 x - 1\right) + \left(4 x - 1\right) + \left(4 x - 1\right)$

Which is the same as$\text{ } 4 x - 1 + 4 x - 1 + 4 x - 1$

Which is the same as$\text{ } 4 x + 4 x + 4 x - 1 - 1 - 1$

Which is the same as $\textcolor{g r e e n}{\text{ } 12 x - 3}$

Notice that you have ended up with the same expression as you would do if you multiplied every thing inside the bracket with 3

Now all you have to do is deal with the negative bit.

$- 1 \times \left(12 x - 3\right) = \left(- 1 \times 12 x\right) + \left(- 1 \times - 3\right)$

$\left(- 12 x\right) + \left(+ 3\right) = - 12 x + 3$

$\textcolor{b l u e}{\text{I hope this helps!}}$