By using the method of completing the square, show that the equation 2x2 + x + 4 = 0 has no real roots.

2x2 + x + 4 = 0

4x2 + 2x + 8 = 0 (multiplying both sides by 2)


4x2 + 2x = - 8


[Adding on both sides]


using a2 + 2ab + b2 = (a + b)2


But cannot be negative for any real value of x


So there is no real value of x satisfying the given equation.


Hence the given equation has no real roots.


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