## anonymous one year ago Evaluate 2x^2y for x = 2 1/2 and y = -3 3/5

1. anonymous

2. anonymous

i plugged in 2(2 1/2) ^2 (-3 3/5)

3. anonymous

$2(2\frac{ 1 }{ 2 })^2 (-3\frac{ 3 }{ 5})$

4. anonymous

I think what will make it a little easier to evaluate would be if you changed the mixed integer into a fraction. $2\frac{1}{2} \iff \frac{(2 \cdot 2)+1}{2}$$-3\frac{3}{5} \iff \frac{(-3 \cdot 5) +3}{5}$

5. anonymous

okay :)

6. anonymous

and from there do i just multiply straight across?

7. anonymous

Yup, you input the fraction in place of x and y and simplify! :)

8. anonymous

okay thanks!

9. anonymous

okay so after that i got 5/2 and then -12/5 is that right?

10. anonymous

Lets check it out. I havent solved it yet! SO we'll see.

11. anonymous

okay! im solving it right now

12. anonymous

i figured it out! thanks

13. anonymous

$x = \frac{ 5}{2} ~,~ y = -\frac{12}{5}$Now let's input these into our formula: $$2x^2y$$ When I put these values in, I got:$2\left(\frac{5}{2}\right)^2\left(\frac{-12}{5}\right)$$2\left(\frac{25}{4}\cdot \frac{-12}{5}\right)$$2(-15) = \boxed{-30}$

14. anonymous

Hmm. i got the answer as -45

15. anonymous

can you write out your steps? Maybe we can compare and see which one of is wrong :o

16. anonymous

I did 2(5^2/2^2) and then -18/5 because i multiped 2*2 then added 1 which gave me 5 so i then put 2(25/4) (-18/5) and then put the 2 into a fraction so 2/1 (25/4) (-18/5) and then i crossed out numbers so i did (2*1/1) (25/2*2) and then it would be 25/2 (-18/5) Cross out numbers again (5*5)/2) (-1*18/5*1) (5/2) (-18/1) = -90/2 = -45

17. anonymous

sorry if you cant understand

18. anonymous

Where did the $$-\frac{18}{5}$$ come from?

19. anonymous

i multiplied -3*5 and added 3

20. anonymous

thank you for helping me! I have to go to school now, the answer sheet said it was -45 so maybe i did something wrong : )

21. anonymous

Well... $$(-3\cdot 5) +3 = -15 + 3 = -12...$$

22. anonymous

yeah i moved the negative sign tho