Study Set:
+15 Math Questions for SAT Prep - Group 2

Based on the system of equations above, what is the value of the product xy?

There are several solution methods possible, but all involve persevering in solving for the two variables and calculating the product. For example, combining like terms in the first equation yields 4x - 4y = 7 and then multiplying that by 2 gives 8x -8y-14. When this transformed equation is added to the second given equation, the y-terms are eliminated, leaving an equation in just one variable:

9x = 18 ,or x =2.

Substituting 2 for x in the second equation (one could use either to solve) yields

2+8y =4 , which gives y =1 /4. Finally, the product xy is 2 * 1/4 =1/2.

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