Math - The FOIL Method

yes just a typo

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Ok. This is what I have.

for -1/3(x-2)(x-8)
f x^2
o -8X
i -2x
l 16x
-1/3(x^2 -10x +16)

-1/3x^2 + 10/3 x - 16/3

y = -1/3(x^2-10x+16) better form than following as nothing is divisible by 3

y = -1/3x^2 + 10/3x -16/3

Check : Replacing x by 2 : -1/3(4-20+16) = 0 , replacing by 8 : -1/3(64-80+16) = 0

Challenge answer:

y = (-1/3 x2) + 10/3x - 16/3

My solution:

x * x = x2
x * -8 = -8x
-2 * x = -2x
-2 * -8 = -16

x2 - 10x + 16
y = (-1/3 x2) + 10/3x - 16/3

Those were some nasty fractions! My answer for the challenge is below.

y = -x^2/3 + 10x/3 - 16/3

Good morning!

Here is mine!

(x - 2)(x - 8)
x^2 ; - 8x ; -2x ; +16
-1/3( x^2 - 10x + 16)

[ 0 = - 1/3 x^2 + 10/3 x - 16/3]

Cheers!

y=-(1/3)x^2+(10/3)x-16/3

(x - 2) * (x - 8) = x^2 - 8x - 2x + 16 = x^2 - 10x + 16
y = -1/3 x^2 + 10/3 x - 16/3

y = -1/3 (x - 2) (x - 8)
y = -1/3 (x^2 - 8x - 2x + 16)
y = -1/3 (x^2 - 10x + 16)
y = -1/3x^2 + 10/3x - 16/3

To begin, this verified that I got my last challenge wrong! :smiley:

Hopefully keeping the improper fractions was okay for this one.

0 = (-1/3)x^2 + (10x/3) - (16/3)

Here’s my answer for the FOIL Method challenge:

Q1. Given y = -1/3(x - 2)(x - 8), convert to standard form.

A1. y = (-1/3)x² + (10/3)x - (16/3)
A1a. (x - 2)(x - 8)
A1b. x² - 8x - 2x + 16
A1c. x² -10x + 16
A1d. (x2 - 10x + 16) * -1/3
A1e. (-1/3)x² + (10/3)x - (16/3)

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Seems like I had the right idea but should have used a fraction instead of a decimal in the middle there.

For this challenge I got:

y = -(1/3)x^2 + (10/3)x - 16/3

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