2006-09-29 12:43:05 · 12 answers · asked by Anonymous in Education & Reference ➔ Homework Help
If you remember the FOIL rule, this type of problem gets really easy!
Foil stands for:
First
Outer
Inner
Last
http://upload.wikimedia.org/math/7/b/6/7b6927267bb234b1f1f470468243ec66.png
So, you do
(x*x)+(x*9)+(-10*x)+(-10*9)
simplify and you get
x^2+9x-10x-90
Now, combine the like terms
x^2-x-90
(^2 means squared)
2006-09-29 12:44:57 · answer #1 · answered by ĵōē¥ → đ 6 · 2⤊ 1⤋
X times (X + 9) = X^2 + 9X
-10 times (X + 9) = -10X -90
Add together:
X^2 + 9X - 10X -90
= X^2 +(9-10)X - 90
= X^2 - X - 90
Let's check:
Let X = 25
a) (25-10)*(25+9) = 15*34 = 510
b) 25^2 - 25 -90 = 625 - 25 - 90 = 510
2006-09-29 20:02:44 · answer #2 · answered by Tom-SJ 6 · 0⤊ 1⤋
first do x times x. then do x times 9. then do -10 times x. then do -10 times 9. add them all. you get
x squared -x -90
2006-09-29 19:47:30 · answer #3 · answered by Anonymous · 0⤊ 1⤋
(x - 10)(x + 9)
x^2 + 9x - 10x - 90
x^2 - x - 90
Remember F * O * I * L
First: x * x = x^2
Outer: x * 9 = 9x
Inner: -10 * x = -10x
Last: -10 * 9 = -90
Good luck in your classes.
2006-09-29 19:46:33 · answer #4 · answered by Mitch 7 · 0⤊ 1⤋
(x-10)(x+9)= x2+9x-10x-90= x2-x-90= (x-10)(x+9)= x=10/x=-9
2006-09-29 19:51:41 · answer #5 · answered by Noble 4 · 0⤊ 1⤋
FOIL it out--Firsts, Outers, Inners, Lasts
x times x
x times 9
-10 times x
-10 times 9
Then combine your like terms.
2006-09-29 19:47:26 · answer #6 · answered by Anonymous · 0⤊ 1⤋
x^2-10x+9x-90=0
then use the quadratic form to get the x
2006-09-30 01:18:07 · answer #7 · answered by John 2 · 0⤊ 1⤋
x^2 -x -90
2006-09-29 19:46:52 · answer #8 · answered by Goddess of Grammar 7 · 0⤊ 1⤋
[first, outside, inside, last]
x^2-x-90
2006-09-30 00:36:22 · answer #9 · answered by Anonymous · 0⤊ 1⤋
x^2 - x - 90 , I think
2006-09-29 19:46:53 · answer #10 · answered by Britt 4 · 0⤊ 1⤋