# more math

Discussion in 'The Okie Corral' started by Atomic Punk, Apr 4, 2012.

1. ### Atomic Punk

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brushing up on some math. have a test for a new job in a few weeks. got some sample questions. i am out of practice but i can figure most of it out. one of the questions i still dont get though.

Y= 3(x+5) (x-2)

multiple choice. wants a formula that is equivalent. says the answer is

Y= 3x2 + 9x - 30

can anyone explain how this works?

2. ### TalkToTheGlockZombie Hunter

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Multiply 3 by (x+5). Equals (3x+15). Then use distributive property to multiply the values (3x + 15) times (x - 2).

Equals..

3x2 - 6x +15x -30. The add equal or like terms and get...

3x2 + 9x -30

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3. ### BlasterHunc tu caveto

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Y= 3(x+5) (x-2)

Y= (3x+15) (x-2)

next FOIL (First Inner Outer Last)

Y= 3x2 + 15x - 6x -30

Y= 3x2 + 9x - 30

4. ### TalkToTheGlockZombie Hunter

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You need to multiply 3x by x And then by negative 2. Then you do the same for 15 and bingo. Hopw I helped.

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5. ### ArtificialGrapeCLM

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3(x+5) (x-2)

Multiply 3 times the expression (x + 5) and right hand becomes

(3x + 15) (x - 2)

Now apply F.O.I.L. -- multiply Firsts, then Outers, then Inners, then Lasts

Firsts = 3x times x = 3x^2
Outers = 3x times -2 = -6x
Inners = 15 times x = 15x
Lasts = 15 times -2 = -30

3x^2 + 9x -30

Good Luck.

Last edited: Apr 4, 2012

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