Evaluate the following expression using the values given:

Find 3x2 - y3 - y3 - z if x = 3, y = -2, and z = -5.

Question

Evaluate the following expression using the values given:

Find 3x2 - y3 - y3 - z if x = 3, y = -2, and z = -5.

whpalmer4 · Answer

$$3x^2-y^3-y^3-z$$Is that the correct expression?  I'm suspicious of the repeated $y^3$ term in there...

kamibug · Answer

In the case that the equation is as @whpalmer4 sates above, the steps for solving would be as follows. Substitute the given values into the equation. 

3(3)^2 - (-2)^3 - (-2)^3 - (-5)
9^2 - 4 - 4 +5
81 -8 +5
81 - 3
78

whpalmer4 · Answer

Mmm…not quite…

$$3x^2-y^3-y^3-z$$$$3(3)^2-y^3-y^3-z=27-y^3-y^3-z$$$$27-(-2)^3-(-2)^3-z = 27-(-8)-(-8)-z = 27+8+8-z = 43-z $$$$43-z = 43-(-5) = 48$$

whpalmer4 · Answer

I did the substitutions one by one so you could see them a bit more clearly.

kamibug · Answer

My mistake was doing y squared instead of cubed.