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#1 Re: Help Me ! » Factoring Quadratics » 2013-06-27 16:51:32

hi mike,bob explained well but i will give some explanation to understand you better

For factors first you have to know 4 formulas
+ * + = +
+ * -  = -
-  * + = -
-  * -  = +

Given equation be 2x^2+7x+3
quadratic equation be ax^2+bx+c=0 so here a=2, b=7, c=3
first multiply 2*3=6
now find the factors for 6
6=1*6
    2*3
    3*2
    6*1
check according the formulas given above to get the value 7 because in given equation the value of B be 7

6*1=6 required factor if you add these you get 7 i.e.,6+1=7

if you add 2+3=5, 5 is the answer which is not the value of b. so take 6 and 1 as factors

+(6) *+(1)=+ (6)     or    +(1) *+(6)=+ (6)

2x^2+7x+3
2x^2+6x+1x+3
2x(x+3)+1(x+3)
(2x+1)(x+3)

#2 Re: Help Me ! » Somebody please tell how to do these factorisation » 2013-06-25 19:35:47

hi bobbym here Agnishom solve all  the problems and he also given hints. i think still you have some confusion.I will explain clearly along with formulas

problem:x^4+8x^2+144
solution: [(x^2)^2+2(x^2)(12)+(12)^2]-16x^2    Formula:(a+b)^2=a^2+2ab+b^2

here (x^2+12)^2 = (x^2)^2+2(x^2)(12)+12^2
If u solve this, the result be x^4+24x^2+144

But in the given question we have 8x^2, we got 24x^2 for that we are subtracting 16x^2 from our result

so the equation be [(x^2)^2+2(x^2)(12)+12^2]-16x^2
                           
                             [(x^2+12)^2]-16x^2   

                             (x^2+12)^2-(4x)^2      Formula(a+b)(a-b)=a^2-b^2

here a=x^2+12  b=4x,      [x^2+12+4x][x^2+12-4x]

Therefore[x^2+4x+12][x^2-4x+12]
smile

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