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Jasmine bought 2 pounds of apples at $$3 per pound and 4 pounds of bananas at $1 per pound. Write an algebraic expression for the cost of Jasmine's purchase.


What would be the correct algebraic expression for the above question?

Would it be

a) ( 3 x 2 ) + (1 x 4)

OR

b) 3a + 1b

Would greatly appreciate your help. Thank you in advance.

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    $\begingroup$ Pounds here, pounds there. What a confusing question. To begin with, change pounds for kilos...or pounds for dollars, pesos or rubles $\endgroup$ – DonAntonio Jan 21 '19 at 23:42
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    $\begingroup$ You are correct in both cases. Case $b$ is the general case and case $a$ is your specific case. $\endgroup$ – John Douma Jan 21 '19 at 23:57
  • $\begingroup$ @JohnDouma why would b) be the correct general case rather than $2c + 1b$ or $2c + 4d$ or $3a + 4d$ or $ac + 4$ or $ac + 4d$ or $6 + bd$ or... or $ac + bd$. You have zero unknowns and four knowns. why would you apply any variables? $\endgroup$ – fleablood Jan 22 '19 at 0:28
  • $\begingroup$ @fleablood I guess the prices could also fluctuate. Still, the answer given is correct. $\endgroup$ – John Douma Jan 22 '19 at 0:45
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Since they're asking for the cost of Jasmine's purchase, I would go with choice (a), since it represents the total cost: $(3 \times 2) + (1 \times 4)$.

That being said, if it's a short-answer homework question, then I'd cover my bases and put the general case and explain the substitution of 2 for a and 4 for b.

Hope this helps!

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Double check the definition of "algebraic expression" in whatever textbook/workbook you are using. Usually, an algebraic expression is defined as being built from constants, variables (a, b, etc), and algebraic operations (+, -, *, /, ^).

Given the above definition for algebraic expression, I would say:

3a + 1b

is the correct answer.

It seems to me that the question is testing whether or not the student can pick-out which numbers are the coefficients and which numbers are specific instances of the variables.

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