Answer:

Step-by-step explanation:
we know that
The equation of a exponential growth function is given by

where
y is the value of the doll
x is the number of years
a is the initial value
r is the rate of change
we have

substitute


What will be the value of the doll in 20 years?
For x=20 years
substitute in the equation

Answer:
i) The augmented matrix for this system is
![\left[\begin{array}{ccc|c}4&-2&-7&4\\2&12&3&-5\\-1&6&2&15\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D4%26-2%26-7%264%5C%5C2%2612%263%26-5%5C%5C-1%266%262%2615%5Cend%7Barray%7D%5Cright%5D)
ii) The reduced row echelon form
![\text{rref}(A)=\left[ \begin{array}{cccc} 1 & 0 & 0 & - \frac{692}{65} \\\\ 0 & 1 & 0 & \frac{423}{130} \\\\ 0 & 0 & 1 & - \frac{493}{65} \end{array} \right]](https://tex.z-dn.net/?f=%5Ctext%7Brref%7D%28A%29%3D%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%200%20%26%20-%20%5Cfrac%7B692%7D%7B65%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%200%20%26%20%5Cfrac%7B423%7D%7B130%7D%20%5C%5C%5C%5C%200%20%26%200%20%26%201%20%26%20-%20%5Cfrac%7B493%7D%7B65%7D%20%5Cend%7Barray%7D%20%5Cright%5D)
iii) The set of solutions are
= -692/65
= 423/130
= -493/65
Step-by-step explanation:
i) An augmented matrix for a system of equations is a matrix of numbers in which each row represents the constants from one equation (both the coefficients and the constant on the other side of the equal sign) and each column represents all the coefficients for a single variable.
We have the following system of equations:

Here is the augmented matrix for this system.
![\left[\begin{array}{ccc|c}4&-2&-7&4\\2&12&3&-5\\-1&6&2&15\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Cc%7D4%26-2%26-7%264%5C%5C2%2612%263%26-5%5C%5C-1%266%262%2615%5Cend%7Barray%7D%5Cright%5D)
ii) To find the reduced row echelon form of
![A=\left[ \begin{array}{cccc} 4 & -2 & -7 & 4 \\\\ 2 & 12 & 3 & -5 \\\\ -1 & 6 & 2 & 15 \end{array} \right]](https://tex.z-dn.net/?f=A%3D%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%204%20%26%20-2%20%26%20-7%20%26%204%20%5C%5C%5C%5C%202%20%26%2012%20%26%203%20%26%20-5%20%5C%5C%5C%5C%20-1%20%26%206%20%26%202%20%26%2015%20%5Cend%7Barray%7D%20%5Cright%5D)
you must:
- Divide row 1 by 4

![\left[ \begin{array}{cccc} 1 & - \frac{1}{2} & - \frac{7}{4} & 1 \\\\ 2 & 12 & 3 & -5 \\\\ -1 & 6 & 2 & 15 \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%20-%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B4%7D%20%26%201%20%5C%5C%5C%5C%202%20%26%2012%20%26%203%20%26%20-5%20%5C%5C%5C%5C%20-1%20%26%206%20%26%202%20%26%2015%20%5Cend%7Barray%7D%20%5Cright%5D)
- Subtract row 1 multiplied by 2 from row 2

![\left[ \begin{array}{cccc} 1 & - \frac{1}{2} & - \frac{7}{4} & 1 \\\\ 0 & 13 & \frac{13}{2} & -7 \\\\ -1 & 6 & 2 & 15 \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%20-%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B4%7D%20%26%201%20%5C%5C%5C%5C%200%20%26%2013%20%26%20%5Cfrac%7B13%7D%7B2%7D%20%26%20-7%20%5C%5C%5C%5C%20-1%20%26%206%20%26%202%20%26%2015%20%5Cend%7Barray%7D%20%5Cright%5D)
- Add row 1 to row 3

![\left[ \begin{array}{cccc} 1 & - \frac{1}{2} & - \frac{7}{4} & 1 \\\\ 0 & 13 & \frac{13}{2} & -7 \\\\ 0 & \frac{11}{2} & \frac{1}{4} & 16 \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%20-%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B4%7D%20%26%201%20%5C%5C%5C%5C%200%20%26%2013%20%26%20%5Cfrac%7B13%7D%7B2%7D%20%26%20-7%20%5C%5C%5C%5C%200%20%26%20%5Cfrac%7B11%7D%7B2%7D%20%26%20%5Cfrac%7B1%7D%7B4%7D%20%26%2016%20%5Cend%7Barray%7D%20%5Cright%5D)
- Divide row 2 by 13

![\left[ \begin{array}{cccc} 1 & - \frac{1}{2} & - \frac{7}{4} & 1 \\\\ 0 & 1 & \frac{1}{2} & - \frac{7}{13} \\\\ 0 & \frac{11}{2} & \frac{1}{4} & 16 \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%20-%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B4%7D%20%26%201%20%5C%5C%5C%5C%200%20%26%201%20%26%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B13%7D%20%5C%5C%5C%5C%200%20%26%20%5Cfrac%7B11%7D%7B2%7D%20%26%20%5Cfrac%7B1%7D%7B4%7D%20%26%2016%20%5Cend%7Barray%7D%20%5Cright%5D)
- Add row 2 multiplied by 1/2 to row 1

![\left[ \begin{array}{cccc} 1 & 0 & - \frac{3}{2} & \frac{19}{26} \\\\ 0 & 1 & \frac{1}{2} & - \frac{7}{13} \\\\ 0 & \frac{11}{2} & \frac{1}{4} & 16 \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%20-%20%5Cfrac%7B3%7D%7B2%7D%20%26%20%5Cfrac%7B19%7D%7B26%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B13%7D%20%5C%5C%5C%5C%200%20%26%20%5Cfrac%7B11%7D%7B2%7D%20%26%20%5Cfrac%7B1%7D%7B4%7D%20%26%2016%20%5Cend%7Barray%7D%20%5Cright%5D)
- Subtract row 2 multiplied by 11/2 from row 3
![\left[ \begin{array}{cccc} 1 & 0 & - \frac{3}{2} & \frac{19}{26} \\\\ 0 & 1 & \frac{1}{2} & - \frac{7}{13} \\\\ 0 & 0 & - \frac{5}{2} & \frac{493}{26} \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%20-%20%5Cfrac%7B3%7D%7B2%7D%20%26%20%5Cfrac%7B19%7D%7B26%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B13%7D%20%5C%5C%5C%5C%200%20%26%200%20%26%20-%20%5Cfrac%7B5%7D%7B2%7D%20%26%20%5Cfrac%7B493%7D%7B26%7D%20%5Cend%7Barray%7D%20%5Cright%5D)
- Multiply row 3 by −2/5

![\left[ \begin{array}{cccc} 1 & 0 & - \frac{3}{2} & \frac{19}{26} \\\\ 0 & 1 & \frac{1}{2} & - \frac{7}{13} \\\\ 0 & 0 & 1 & - \frac{493}{65} \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%20-%20%5Cfrac%7B3%7D%7B2%7D%20%26%20%5Cfrac%7B19%7D%7B26%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B13%7D%20%5C%5C%5C%5C%200%20%26%200%20%26%201%20%26%20-%20%5Cfrac%7B493%7D%7B65%7D%20%5Cend%7Barray%7D%20%5Cright%5D)
- Add row 3 multiplied by 3/2 to row 1

![\left[ \begin{array}{cccc} 1 & 0 & 0 & - \frac{692}{65} \\\\ 0 & 1 & \frac{1}{2} & - \frac{7}{13} \\\\ 0 & 0 & 1 & - \frac{493}{65} \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%200%20%26%20-%20%5Cfrac%7B692%7D%7B65%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%20%5Cfrac%7B1%7D%7B2%7D%20%26%20-%20%5Cfrac%7B7%7D%7B13%7D%20%5C%5C%5C%5C%200%20%26%200%20%26%201%20%26%20-%20%5Cfrac%7B493%7D%7B65%7D%20%5Cend%7Barray%7D%20%5Cright%5D)
- Subtract row 3 multiplied by 1/2 from row 2

![\left[ \begin{array}{cccc} 1 & 0 & 0 & - \frac{692}{65} \\\\ 0 & 1 & 0 & \frac{423}{130} \\\\ 0 & 0 & 1 & - \frac{493}{65} \end{array} \right]](https://tex.z-dn.net/?f=%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%200%20%26%20-%20%5Cfrac%7B692%7D%7B65%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%200%20%26%20%5Cfrac%7B423%7D%7B130%7D%20%5C%5C%5C%5C%200%20%26%200%20%26%201%20%26%20-%20%5Cfrac%7B493%7D%7B65%7D%20%5Cend%7Barray%7D%20%5Cright%5D)
The answer is
![\text{rref}(A)=\left[ \begin{array}{cccc} 1 & 0 & 0 & - \frac{692}{65} \\\\ 0 & 1 & 0 & \frac{423}{130} \\\\ 0 & 0 & 1 & - \frac{493}{65} \end{array} \right]](https://tex.z-dn.net/?f=%5Ctext%7Brref%7D%28A%29%3D%5Cleft%5B%20%5Cbegin%7Barray%7D%7Bcccc%7D%201%20%26%200%20%26%200%20%26%20-%20%5Cfrac%7B692%7D%7B65%7D%20%5C%5C%5C%5C%200%20%26%201%20%26%200%20%26%20%5Cfrac%7B423%7D%7B130%7D%20%5C%5C%5C%5C%200%20%26%200%20%26%201%20%26%20-%20%5Cfrac%7B493%7D%7B65%7D%20%5Cend%7Barray%7D%20%5Cright%5D)
iii) The set of solutions are
= -692/65
= 423/130
= -493/65
Answer:
The answer is five
Step-by-step explanation:
Because 5 times 3 equals 15.
That's just basic multiplying. (*^*)
Have a good day!
Answer:
52
Step-by-step explanation:
everytime it adds by 9:
7+9=16
16+9=25
25+9=34
34+9=43
<u>43+9=52</u>