Evaluate when x=3 and y=-5
(2x)^3+y^3
My figuring:
2*3=6, 6*6*6=216
(-5)(-5)(-5)=-125
Solution: 91
According to my teacher, the answer should be -7, not 91. Who is right, and why?
(2x)^3+y^3
= (6)^3 + (-5)^3
= 216 + (-125)
= 91
If you typed the question correctly, and those are the values of x and y, then 91 is the correct answer.
Ok thank you
To evaluate the expression (2x)^3 + y^3 when x = 3 and y = -5, you correctly substituted the values of x and y into the expression:
(2*3)^3 + (-5)^3
(6)^3 + (-5)^3
216 + (-125)
91
However, it seems there may be a discrepancy between your calculation and what your teacher is expecting. To verify who is correct, let's go through the steps again.
According to the order of operations/precedence rules in mathematics, exponentiation should be performed before addition. Therefore, let's simplify (2x)^3 and y^3 individually before adding them together.
(2x)^3 = (2*3)^3 = 6^3 = 216
y^3 = (-5)^3 = -5 * -5 * -5 = -125
Now, let's add the two simplified values:
216 + (-125) = 216 - 125 = 91
Based on the correct application of the order of operations, the answer should be 91, not -7. It's possible that either your teacher made a mistake or there may have been a misunderstanding. However, according to the given information and following the standard mathematical rules, the solution is 91.