# CBSE Class 10-Mathematics: Chapter –4 Quadratic Equations Part 27

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**Question 18:**

Find the roots of the following quadratic equations if they exist by the method of completing square.

(i)

(ii)

(iii)

(iv)

**Answer:**

(i)

First, we divide equation by to make coefficient of equal to ,

We divide middle term of the equation by , we get

We add and subtract square of from the equation

Taking Square root on both sides,

And

Therefore,

(ii)

Dividing equation by ,

Following procedure of completing square,

Taking square root on both sides,

Therefore,

(iii)

Dividing equation by ,

Following the procedure of completing square,

Taking square root on both sides,

(iv)

Dividing equation by 2,

Following the procedure of completing square,

Taking square root on both sides

Right hand side does not exist because square root of negative number does not exist.

Therefore, there is no solution for quadratic equation