would this be 9x^2-81 ??? if not please explain. Thank you.
2007-05-17 14:59:56 · 6 answers · asked by whattheheck 4 in Science & Mathematics ➔ Mathematics
(3x-9)^2 = (3x -9)(3x-9)
9x^2 - 54 x +81
the shortcut for calculating the equation is
(3x)^2 + (3x)(-9)(2) + (9^2)
2007-05-17 15:05:03 · answer #1 · answered by misshahila 2 · 1⤊ 1⤋
No, either you can use the foil method or the bionomial theorm which is (x - y)^2 = x^2 - 2xy + y^2
So using foil first....
Rewrite (3x - 9)^2 as...
(3x - 9)(3x - 9) now use foil
9x^2 - 27x - 27x + 81 now add like terms
9x^2 - 54x + 81 this is your final answer.
Now doing it using the theorm we get...
(3x - 9)^2 now your x in theorm is equal to 3x and your y in the theorm is equal to 9.... so we get...
(3x)^2 - 2(3x)(9) + (9)^2 which equals
9x^2 - 54x + 81
Notice both ways we get the same answer.
If you need further help or clarification email me or im me. Good Luck.
2007-05-17 22:07:13 · answer #2 · answered by Anonymous · 1⤊ 0⤋
nope.
(3x - 9 ) ^2 also means (3x - 9)(3x - 9)
then you multiply 3x and 3x. multiply 3x and (-9). mutiply (-9) and 3x and then (-9) and (-9)
then you should get 9x^2 - 54 + 81
2007-05-17 22:10:37 · answer #3 · answered by cynthia © 3 · 1⤊ 0⤋
(3x-9)^2
(3x)^2=9x^2
3x*9*2(its doubled because you are squaring the polynomial)
9x^2-54x
(-9)^2=-9*-9=81
9x^2-54x+81
2007-05-17 22:07:09 · answer #4 · answered by Dave aka Spider Monkey 7 · 1⤊ 1⤋
(3x-9)^2
(3x-9)(3x-9)
Now multiply each term
9x² - 27x -27x + 81
Combine terms
9x² - 54x + 81
.
2007-05-17 22:05:13 · answer #5 · answered by Robert L 7 · 1⤊ 1⤋
(3x-9)^2
9x^2-54x-81
source----(a-b)^2=a^2-2ab+b^2
2007-05-17 22:15:26 · answer #6 · answered by sam 3 · 0⤊ 0⤋