# Question #59ec4

Apr 8, 2017

See the entire solution process below:

#### Explanation:

The sequence takes the difference between the two previous numbers, doubles it, and adds this to the last number in the sequence:

Looking at the first two terms in the sequence:

$9 - 4 = 5$; $5 \times 2 = 10$, add it to the last number, $9 + 10 = 19$

Now, look at $9$ and $19$:

$19 - 9 = 10$; $10 \times 2 = 20$, add it to the last number, $19 + 20 = 39$

Now, look at $19$ and $39$:

$39 - 19 = 20$; $20 \times 2 = 40$, add it to the last number, $39 + 40 = 79$

The missing term in the sequence is: $\textcolor{red}{39}$

Apr 8, 2017

$39$

#### Explanation:

Apparently the differnce between term doubles every time:

$4 + 5 = 9$

$9 + 10 = 19$

$19 + 20 = 39$

$39 + 40 = 79$

The next term will be:

$79 + 80 = 159$