Use a Graphing Calculator and the Method of Matrix Inverses $\$ 4.06$

question 109

Multiple Choice

Use a graphing calculator and the method of matrix inverses to Give five decimal places, if necessary.
-Matt bought 3 pounds of oranges and 2 pounds of apples and paid $\$ 4.06$ , before tax. Andy bought 4 pounds of oranges and 3 pounds of apples and paid \$5.71, before tax. Use this information to set up a matrix equation of the form $\mathrm { AX } = \mathrm { B }$ , which can be solved to determine the price per pound for oras and apples. Solve this matrix equation to find the price per pound of apples.
Use the fact that for $A = \left[ \begin{array} { l l } 3 & 2 \\ 4 & 3 \end{array} \right] , A ^ { - 1 } = \left[ \begin{array} { r r } 3 & - 2 \\ - 4 & 3 \end{array} \right]$ .

• A) \(\$ 0.89\) per pound
• B) \(\$ 0.86\) per pound
• C) \(\$ 0.80\) per pound
• D) \(\$ 0.93\) per pound

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