76th Problem 2016

Algebra Level 2

What is the nature of the roots of this equation:

2 x 2 5 x = 3 { 2x }^{ 2 }-5x=3


Check out the set: 2016 Problems

Not Real Real and Equal Real and Distinct

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2 solutions

Ashish Menon
Mar 23, 2016

The nature of the roots can be found out by finding the discriminant which can in turn be found by applying the formula:- b 2 4 a c b^2 - 4ac

The equation can be written as 2 x 2 5 x 3 = 0 2x^2 -5x-3=0
Here, a = 2 ; b = 5 ; c = 3 a = 2 ; b = -5 ; c = -3
D = ( 5 ) 2 ( 4 × 2 × 3 ) D = {(-5)}^2 - (4×2×-3)
D = 25 ( 24 ) D = 25- (-24)
D = 25 + 24 D = 25+24
D = 49 D = 49 which is greater than zero and a perfect square.
So, the roots of the equation are real, rational and distinct.

Typo: 2 x 2 5 x 3 = 0 2x^2-5x-3=0

Hung Woei Neoh - 5 years ago

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Oh well, yrah thanks! I edited it. :)

Ashish Menon - 5 years ago
Munem Shahriar
Mar 17, 2018

2 x 2 5 x = 3 2 x 2 5 x 3 = 0 2 x 2 6 x + x 3 = 0 2 x ( x 3 ) + ( x 3 ) = 0 ( 2 x + 1 ) ( x 3 ) = 0 x = 1 2 , x = 3 \begin{aligned} 2x^2 - 5x & = 3 \\ 2x^2 - 5x - 3 & = 0 \\ 2x^2 - 6x + x - 3 & = 0 \\ 2x(x - 3) + (x-3) & = 0 \\ (2x + 1)(x-3) & = 0 \\ \implies x = \dfrac {-1}2, x = 3 \\ \end{aligned}

Hence the roots of this equation are real and distinct.

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