For what values of theta (0 less than or equal to theta less than or equal to 2pie) do maximum r-values occur on the graph the polar equation r = 2cos 4theta? Note that the maximum r-value occurs at a point that is the maximum distance from the pole.

9514 1404 393

  $2.50

Step-by-step explanation:

The question asks for the total cost of a notebook and pen together. We don't need to find their individual costs in order to answer the question.

Sometimes we get bored solving systems of equations in the usual ways. For this question, let's try this.

The first equation has one more notebook than pens. The second equation has 4 more notebooks than pens. If we subtract 4 times the first equation from the second, we should have equal numbers of notebooks and pens.

  (8n +4p) -4(3n +2p) = (16.00) -4(6.50)

  -4n -4p = -10.00 . . . . . . . . . . . simplify

  n + p = -10.00/-4 = 2.50 . . . . divide by the coefficient of (n+p)

The total cost for one notebook and one pen is $2.50.

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Additional comment

The first equation has 1 more notebook than 2 (n+p) combinations, telling us that a notebook costs $6.50 -2(2.50) = $1.50. Then the pen is $2.50 -1.50 = $1.00.

One could solve for the costs of a notebook (n) and a pen (p) individually, then add them together to answer the question. We judge that to be more work.