Quadratic and Fractions

Level 1

What is the only positive integer value of x x that satisfies these equations:

y = 3 x 2 + 5 x + 2 y=3x^2+5x+2

y = 132 x 6 y=\frac {-132}{x-6}


The answer is 3.

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3 solutions

The two equations can be simplified and equated. This yields:

( 3 x + 2 ) ( x + 1 ) ( x 6 ) (3x+2)(x+1)(x-6) = = 132 -132

132 -132 can be written as 11 × 4 × 3 11\times4\times-3

Equating the polynomials to the factors, the only combination that is equal is when 3 x + 2 = 11 3x+2=11 , x + 1 = 4 x+1=4 and x 6 = 3 x-6=-3

Thus, x = 3 x=\boxed{3}

but if I change the sequence of your order I mean -3 x 11 x 4 then the answer comes wrong

Musab Naseem - 7 years ago
Rishi Evans
Apr 29, 2014

since the value of y is positive....then y=[1,2,3,4,5]........by hit and trail 3 will satisfy both the equations .

Marcel Rodd
Dec 20, 2013

3x^2 + 5x + 2 = (x+1)(3x+2) = -132/x-6 = 132/6-x = 2 2 3*11/6-x Since x>0 and x is an integer, x only can take values 2, 3, 4 and 5. And by simple evaluation, we get x=3

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