[-3x+ 7/2 ] [-3x- 3/4]
i have 9x^2 + 21/2x -21/8
why is this not correct, where am i going wrong?
2006-10-08 06:46:43 · 9 answers · asked by colecole1979 1 in Education & Reference ➔ Homework Help
ok,but the system is stating that the answer is correct 9x^2-33/4x-21/8 is not in the correct form... what is the form? i thought that was the correct form with all matching variables in order...
2006-10-08 07:03:13 · update #1
-3x(-3x-3/4) +7/2 (-3x-3/4)
=9x^2 +9x/4 -21x/2 -21/8
=9x^2 +9x/4-42x/4 - 21/8
=9x^2 - 33x/4 - 21/8 or 9x^2 - 33/4x -21/8
2006-10-08 06:53:30 · answer #1 · answered by S A 3 · 0⤊ 0⤋
Hmmm, i'd say you've missed something in the middle there :).
Let's start from the top:
[-3x+ 7/2 ] [-3x- 3/4] = 9x^2 -3x(7/2-3/4)-21/8
= 9x^2 -3x(14/4-3/4)-21/8 = 9x^2 -3x(11/4)-21/8
=9x^2 -(33/4)x-21/8
There you go my friend :).
2006-10-08 13:54:58 · answer #2 · answered by Wormer 2 · 0⤊ 0⤋
youre foiling right?
First (-3x)(-3x) = 9x^2
Outer (-3x)(-3/4) = 9/4x
Inner (7/2)(-3x) = -21/2x
Last (7/2)(-3/4) = -21/8
Add Outer & Inner (9/4x)+(-21/2x) = -33/4x
Combine 9x^2 - 33/4x - 21/8
or 9x^2 - 8.25x - 2.625
im not sure where you went wrong exactly..it might just be plugging it in your calculator wrong...and i know thats a really broken down/elementary way of explaining it, but there you go...hope it helped :)
2006-10-08 14:03:09 · answer #3 · answered by BK 1 · 0⤊ 0⤋
[-3X+7/2][-3X-3/4]=[9X^2+9/4X-21/2X-21/8]=[9X^2+9/4X-
{21/2X*2/2}-21/8]=[ 9X^2+9/4X-42/4X-21/8]=[9X^2+33/4X-21/8]. YOU HAVE NEGLECTED[ -3X*-3/4] TERM
2006-10-08 14:03:35 · answer #4 · answered by HELPER 2 · 0⤊ 0⤋
Your middle term is wrong. Use your FOIL rule.
The coefficient of x should be -21/2 + 9/4 = -33/4.
2006-10-08 13:51:02 · answer #5 · answered by steiner1745 7 · 2⤊ 0⤋
9x^2 - 21/2x -21/8 + 9/4x is the right answer
This is the formula
(a+b)(c+d)
ac+ad+bc+bd
2006-10-08 13:51:18 · answer #6 · answered by AlvaDaGansta 4 · 1⤊ 1⤋
=9x^2-9x/4-21x/2-21/8
=9x^2+(9-42/4)x-21/8
=9x^2-33/4x-21/8
2006-10-08 13:52:40 · answer #7 · answered by snow l 3 · 1⤊ 0⤋
The third answer is correct. I will not expand on this but leave it to you to substitute in your numbers for the answer.
Any answer in the above showing no factor of x is very wrong.
2006-10-08 13:57:17 · answer #8 · answered by charlie 2 · 0⤊ 0⤋
you forgot the +9/4 x
2006-10-08 13:51:14 · answer #9 · answered by La-Vie-En-Rose 2 · 1⤊ 1⤋