Find the roots of the following quadratic equations, if they exist, by the method of completing the square:
(i) 
(ii) 
(iii) 
(iv) 
i) 2x2 – 7x +3 =0
Dividing by coefficient of 
=
Adding and subtracting the square of 
= 
= 
= 
= 
= 
So,
= 
When, 
= 
When, 
= 
ii) 2x2 + x – 4 = 0
Dividing by coefficient of 
= 
Adding and subtracting the square of 
= 
= 
= 
= 
Taking square root , we get,
= 
= x = 
∴ x = 
iii) 
Compare the quadratic equation with 
= 
= 
= 
= 
∴ Roots of equation are = x = 
iv) 2x2 + x + 4
Divide by coefficient of 
= 
Adding and subtracting the square of 
= 
= 
= 
= 
Square of a number cannot be negative, Hence roots of following equation do not exist.
3