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Current Student
Joined: 31 Aug 2007
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what's the easiest way to solve these types:
5(t^2)-14t-24=0
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Manager
Joined: 02 Feb 2007
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i think there is always more than one way, but i did this:
5t^2-14t-24=0
5t^2-14t=24
t(5t-14)=24
t=24 and 5t=14, t=14/5
young_gun wrote: what's the easiest way to solve these types:
5(t^2)-14t-24=0
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CEO
Joined: 17 Nov 2007
Posts: 3594
Concentration: Entrepreneurship, Other
Schools: Chicago (Booth) - Class of 2011
GMAT 1: 750 Q50 V40
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michaelny2001 wrote: t(5t-14)=24
t=24 and 5t=14, t=14/5
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Director
Joined: 08 Jun 2007
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walker wrote: michaelny2001 wrote: t(5t-14)=24
t=24 and 5t=14, t=14/5
t(5t-14)=24
t=24 and 5t=14, t=14/5
this is wrong i guess
Way to solve simple quadratic equations
x^2 - 5x + 6 = 0=> break the middle term such that its product is equal to the product of end terms
x^2 -3x -2x +6 = 0
x(x-3) - 2(x-3) = 0
(x-2)(x-3) = 0
Roots are 2 and 3 .
If equations are not simple apply direct formula for roots for equations like ax^2 + bx +c = 0
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Manager
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If I can't transform equation into the basic multiples, I use formula above.
But GMAT usually uses equations that are easily transformed into the form (a + b) * (a + c) or analogues
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CEO
Joined: 17 Nov 2007
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There a general shortcut for equation like:
x^n+a*x^(n-1)+....+g=0
if g integer your roots probably will be among +/-factors of g.
For example:
x^2 -3x -2x +6 = 0
g=6 ==> {-6,-3,-2,-1,1,2,3,6} - both roots are in the set
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Director
Joined: 09 Aug 2006
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young_gun wrote: what's the easiest way to solve these types:
5(t^2)-14t-24=0
24*5 = 120; If we take -20 and 6 as factors then sum = -20+6 = -14
5t^2 - 20t + 6t - 24 = 0
5t(t-4)+6(t-4) = 0
(5t+6)(t-4) = 0
t=-6/5 or t=4
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CEO
Joined: 29 Mar 2007
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ashkrs wrote: walker wrote: michaelny2001 wrote: t(5t-14)=24
t=24 and 5t=14, t=14/5
t(5t-14)=24 t=24 and 5t=14, t=14/5 this is wrong i guess Way to solve simple quadratic equations x^2 - 5x + 6 = 0=> break the middle term such that its product is equal to the product of end terms x^2 -3x -2x +6 = 0 x(x-3) - 2(x-3) = 0 (x-2)(x-3) = 0 Roots are 2 and 3 . If equations are not simple apply direct formula for roots for equations like ax^2 + bx +c = 0 O damn highschool math. forgot all bout that quadratic formula thing.
What is it even called. Thats pretty handy actually.
essentially x=(14+/-26)/10 --> x=6/5 or 4
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Director
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GK_Gmat wrote: young_gun wrote: what's the easiest way to solve these types:
5(t^2)-14t-24=0 24*5 = 120; If we take -20 and 6 as factors then sum = -20+6 = -14 5t^2 - 20t + 6t - 24 = 0 5t(t-4)+6(t-4) = 0 (5t+6)(t-4) = 0 t=-6/5 or t=4
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