Correct?

[jeffeh]

Is this correct?

Question 3

 

[meltdown75]

JEFFEH!

 

[maximus maximus]

Wrong (2x - 1)^2 is 4x^2 + 1 - 4x

because (a-b)^2 = a^2 + b^2 - 2ab

 

[jeffeh]

yes?

 

[maximus maximus]

Originally posted by: jeffeh
Is this correct?

Question 3

Your math formulas are weak man.

 

[jeffeh]

ahh I see, thanks maximus

 

[maximus maximus]

Originally posted by: jeffeh
ahh I see, thanks maximus

Correct it in both the problems.

 

[jeffeh]

why -2ab though,.. thats not how we were taught

 

[maximus maximus]

Originally posted by: jeffeh
why -2ab though,.. thats not how we were taught

You were thought wrong.

Let me tell you why it it that way. (* = multiply okay)

(a-b) ^ 2
= (a - b) * (a -b)
= a^2 - b*a - a*b + b^2
= a^2 - a*b - a*b + b^2
= a^2 - 2*a*b + b^2

Hope that answers your question

 

[maximus maximus]

Let me also give you a tip. To verify any formula, substitute a couple of values both on the right hand side and the left hand side of the euqation to check it.

For example a = 4 and b = 1

Therefore left side of the equations is (a-b)^2 = (4-1)^2 = 3^ 2 = 9

Right side of the equation is a^2 - 2*a*b + b^ 2 = 4^2 - 2.4.1 + 1^ 2 = 16 - 8 + 1 = 9

 

[simms]

*slaps head* so this is what happened to the education system in Ontario after they got rid of OAC...

 

[meltdown75]

Originally posted by: simms
*slaps head* so this is what happened to the education system in Ontario after they got rid of OAC...

AHHAHAHAHAH :thumbsup:

 

[jeffeh]

Oh ok I see, thanks

 

[JulesMaximus]

Ban. Do your own homework.

 

[tikwanleap]

They should have taught you "F.O.I.L.".

(A + B) * (C + D)

F.O.I.L

First = AC
Outside = AD
Inside = BC
Last = BD

(A + B) * (C + D) = AC + AD + BC + BD

 

[maximus maximus]

Originally posted by: JulesMaximus
Ban. Do your own homework.

He is doing his own homework, he is just asking for some help here. I dont think there is anythig wrong with that.

 

[talyn00]

Originally posted by: tikwanleap
They should have taught you "F.O.I.L.".

(A + B) * (C + D)

F.O.I.L

First = AC
Outside = AD
Inside = BC
Last = BD

(A + B) * (C + D) = AC + AD + BC + BD

so whats what FOIL stood for.... I used it all the time, just never really knew what it was.

 

[Syringer]

Although it's not right anyway..

-3(4x^2-1) does not equal

-3*4 - 3x^2 - 1

 

[jeffeh]

(4x-5)(2x+1) - 3(2x-1)^2
=(8x^2 + 4x - 10x -5) - 3(2x-1)(2x-1)
=(8x^2 + 4x - 10x -5) - 3(4x^2 - 2x - 2x + 1)
=(8x^2 + 4x - 10x -5) - 12x^2 + 6x +6x - 3
=8x^2 - 12x^2 + 4x +6x +6x -10x - 5-3
=-4x^2+6x-8

correct?

 

[jeffeh]

tried to apply all the different stuff mentioned above into question 3)a) hopefully its correct

 

[maximus maximus]

Originally posted by: jeffeh
(4x-5)(2x+1) - 3(2x-1)^2
=(8x^2 + 4x - 10x -5) - 3(2x-1)(2x-1)
=(8x^2 + 4x - 10x -5) - 3(4x^2 - 2x - 2x + 1)
=(8x^2 + 4x - 10x -5) - 12x^2 + 6x +6x - 3
=8x^2 - 12x^2 + 4x +6x +6x -10x - 5-3
=-4x^2+6x-8

correct?

Correctamundo.