Answer:
[tex]b_1=\left(\begin{array}{ccc}-3\\3\end{array}\right),b_2=\left(\begin{array}{ccc}-\dfrac{65}{11}\\\\-\dfrac{19}{11}\end{array}\right)[/tex]
Step-by-step explanation:
Given matrix A and AB below:
[tex]A=\left(\begin{array}{ccc}1&-4\\-4&5\end{array}\right)\\\\\\ AB=\left(\begin{array}{ccc}-10&1&9\\7&-15&8\end{array}\right)[/tex]
For the product AB to be a 2 X 3 matrix, B must be a 2 X 3 matrix.
Let matrix B be defined as follows
[tex]B=\left[\begin{array}{ccc}a&c&e\\b&d&f\end{array}\right][/tex]
Therefore:
[tex]\left(\begin{array}{ccc}1&-4\\-4&5\end{array}\right)\left(\begin{array}{ccc}a&c&e\\b&d&f\end{array}\right)=\left(\begin{array}{ccc}-10&1&9\\7&-15&8\end{array}\right)[/tex]
This results in the equations
Solving the first two equations simultaneously
a-4b=-10 (a=-10+4b)
-4a+5b=7
Substitution of [tex]a=-10+4b[/tex] into the second equation
[tex]-4(-10+4b)+5b=7\\40-16b+5b=7\\-11b=-33\\b=3[/tex]
Recall that [tex]a=-10+4b[/tex]
[tex]a=-10+4(3)=-10+7\\a=-3[/tex]
Solving the other two equations
c-4d=1 (c=1+4d)
-4c+5d=-15
Substitution of c=1+4d into the second equation
[tex]-4(1+4d)+5d=-15\\-4-16d+5d=15\\-11d=19\\d=-\dfrac{19}{11}\\ Recall: c=1+4d\\c=1+4(-\frac{19}{11})\\c=-\dfrac{65}{11}[/tex]
Therefore, we have:
[tex]a=-3, b=3, c=-\dfrac{65}{11}, d=-\dfrac{19}{11}[/tex]
Thus:
[tex]b_1=\left(\begin{array}{ccc}-3\\3\end{array}\right)\\\\\\b_2=\left(\begin{array}{ccc}-\dfrac{65}{11}\\\\-\dfrac{19}{11}\end{array}\right)[/tex]
Answer:
option c
Step-by-step explanation:
it is said that a computer repairman makes 25 dollars per hour
this column shows the right amount of money he earns per hour
