Let y = 2g + x^2 and g = 5x + 1.
If g^2 = 81, then which of the following can be a value of 2y + 3g?
Choices.
A) 52	B) -55	C) 141	D) 142	E) 160
800score Official Solution:   First note that g can either be 9 or -9. We are going to have to use both to find all solutions before we can choose a final answer. We begin by substituting g = 9 and then g = -9. If g = 9, then x = 8/5. If g = -9, then x = -2. Since all of our solutions are whole numbers, we can dismiss 8/5. We use g = -9 and x = -2 to determine the value of y: y = 2(-9) + 4 = -14. Finally, we substitute the values for y and g into the last expression to determine its value : 2(-14) + 3(-9) = -28 - 27 = -55;the correct answer is (-55).
<result>B</result>
Let y = 2g + x^2 and g = 5x + 1.
If g^2 = 81, then which of the following can be a value of 2y + 3g?