## mikevucina 3 years ago how do i evaluate this expression: x(x + y) when x=-2 1/2 and y= 3 3/4?

1. bahrom7893

just plug them in.

2. bahrom7893

(-5/2)*((-5/2)+(15/4))

3. bahrom7893

come on, you can finish the rest...

4. bahrom7893

(-5/2)*((15/4) - (10/4))

5. bahrom7893

(-5/2)*(5/4) = -25/8

6. dgo

mikevucina do you get how to do it?

7. mikevucina

i do know

8. mikevucina

now

9. dgo

do you know the order of operations?

10. mikevucina

ye

11. dgo

what comes first parentheses or multiplication? pop quiz lol

12. mikevucina

parentheses

13. dgo

nice

14. mikevucina

okay 3x squared when x= -1.5 is 6.25?

15. dgo

what comes first, exponents or multiplication?

16. mikevucina

exponents

17. dgo

btw im just learning this myself with you

18. mikevucina

true

19. dgo

bahrom do you square the integer first and then multiply by 3?

20. mikevucina

square number first then integer i think

21. dgo

i think you square the x (which is -1.5 and then multiply by 3

22. dgo

unless its (3x)squared

23. mikevucina

it is

24. dgo

because parentheses comes before exponents

25. bahrom7893

sorry where?

26. dgo

3x squared when x= -1.5

27. bahrom7893

depends on the parenthesis

28. mikevucina

question is 3x squared + 5x - 12 when x= -1.5

29. dgo

are there parentheses?

30. mikevucina

no

31. dgo

so exponents come first, -1.5^2 = what?

32. mikevucina

2.25

33. dgo

so now rewrite the equation

34. dgo

with the new piece of info

35. mikevucina

6.75 + 5x - 12

36. dgo

boom, and we can go ahead and do the 5x, its 5 * 2.25

37. dgo

oops

38. dgo

i mean 5 *x or 5* -1.5

39. dgo

can you do that and then rewrite the equation with the new info?

40. mikevucina

the answer should be 19.25 but i got 11.25?

41. dgo

hmmm, guess we need help, im asking bahrom

42. bahrom7893

can you guys draw out the actual question?

43. dgo

question is 3x2 + 5x - 12 where x = -1.5

44. dgo

3x^2

45. bahrom7893

3*(-1.5)^2+5*(-1.5)-12= 3*(2.25)-5*(1.5)-12

46. dgo

howd you make it -5 in the second line?

47. bahrom7893

6.75-7.5-12= -12.5

48. bahrom7893

5*(-1.5) that negative in front of -1.5 makes the whole thing negative

49. mikevucina

answer is supposed to be 19.25

50. dgo

ok, so that looks good. mike youre saying that the answer should be 19.25? thats weird, bahrom looks right to me, i mean it makes sense

51. bahrom7893

|dw:1329168853490:dw|

52. mikevucina

it says that in the book

53. mikevucina

and bahroom thats the equation

54. bahrom7893

the book's wrong

55. dgo

mike does bahrom's answer make sense to you?

56. mikevucina

ye it does

57. dgo

if so, forget the book

58. dgo

59. dgo

thanks bahrom, im giving him a medal for this, for sure

60. bahrom7893

lol finally haha medals...

61. dgo

lol win! good luck mike, cya around