SOLUTION: You answered this question wrong, because the poster wrote it wrong: If x = –1 and y = 2, what is the value of the expression 2x3 – 3xy ? The actual question is this

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: You answered this question wrong, because the poster wrote it wrong: If x = –1 and y = 2, what is the value of the expression 2x3 – 3xy ? The actual question is this      Log On


   

Question 144397: You answered this question wrong, because the poster wrote it wrong: If x = –1 and y = 2, what is the value of the expression 2x3 – 3xy ?
The actual question is this: If x = –1 and y = 2, what is the value of the expression 2x^3 – 3xy?
I know the answer is 4. But I don't know HOW to get there.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
2x%5E3-3xy Start with the given expression


2%28-1%29%5E3-3%28-1%29%282%29 Plug in x=-1 and y=2


2%28-1%29-3%28-1%29%282%29 Cube -1 to get -1


-2-3%28-1%29%282%29 Multiply 2 and -1 to get -2


-2-3%28-2%29 Multiply -1 and 2 to get -2


-2%2B6 Multiply -3 and -3 to get +6


4 Add -2 and 6 to get 4



So 2x%5E3-3xy=4 when x=-1 and y=2