Question

I need to turn this (x-24)(x-18) into a quadratic equation using reverse foil method. PLEASE HELP

Answer 1

It's not the reverse FOIL method... It's just FOIL. So you multiply First, Outside, Inside, and Last.

Answer 2

thatt's what I thought but we have to work our problem like this:
go from this: (x – 5)(x – 18) = 0
to this: 2x2 – 40x + 200 = 6x + 20

Answer 3

reverse FOIL? so LIOF?

Answer 4

I guess....i'm totally confused

Answer 5

(x-24)(x-18) = x(x-18) -24(x-18) = x^2 - 18x - 24x + 432 = x^2 - 42x + 432

Answer 6

Okay so first, is x*x
outside is x*-18
inside is x*-5
last is -5*-18

Combine all that and you get this:
\[x^2 - 18x - 5x + 90\]
Simplified:
\[x^2 - 23x + 90\]

Answer 7

& put a zero @ the R.H.S LOL;)

Answer 8

I would have, of course, but I think fee only needed the equation... not to solve it

Answer 9

ok how do you go from (x-5)(x-18)=0 to 2x^2 – 40x + 200 = 6x + 20

Answer 10

\[\LARGE{Hint:-(a+b)(c+d)=a(c+d)+b(c+d)}\]

Answer 11

in this formula what is d?

Answer 12

a,b,c,d are assumed as constants .

here u only assume
a=x
b=24
c=x
d=18

Answer 13

& this equation also can simplified by the identity\[\LARGE{(x+a)(x+b)=x^2+(a+b)x+ab}\]

Answer 14

here a=24 & b=18.

Answer 15

x remains same according to ur equation.

Answer 16

gt it ??

can u do it @Fee ?

Answer 17

so after plugging everything in it should look like this:
(x+24)(x+18)=x^2+(24+18)x+24*18

Answer 18

yup :)

Answer 19

x^2+42x+432.

Answer 20

ohh ! u don't look the sign it's not positive here it's negative therefore it will look like x^2-(24+18)x+24*18 hence we gt x^2-42x+432.

Answer 21

\[\LARGE{(x-a)(x-b)=x^2-(a+b)x+ab}\]

Answer 22

What was wrong with my methods?

Answer 23

@Hero nothing....same thing

I get all those steps but in the example we were given it started off with 2 numbers: 5 and 18

Answer 24

from there t shows (x-5)(x-18)

Answer 25

actually i'm only teaching him other methods but in this question he is said to solve the question through FOIL method so ur method isn't wrong @Hero :)

Answer 26

then from there it says apply rules of algebra to arrive at this: 2x^2 – 40x + 200 = 6x + 20 this is where I get lost

Answer 27

(x – 5)(x – 18) = `x(x-18) -5(x - 18) = x^2 - 18x - 5x + 90` = x^2 - 23x + 90 = 0

Answer 28

then we have to factor back down to the starting point

Answer 29

2x^2 -40x + 200 = 0
x^2 - 20x + 100 = 0
x^2 - 10x - 10x + 100 = 0
x(x - 10) - 10(x-10) = 0
(x - 10)(x - 10) = 0
(x - 10)^2 = 0

Answer 30

x - 10 = 0
x = 10

Answer 31

If you're still confused, I can show you step by step on vyew