# Chapter 8: Quadratic Equations Exercise – 8.4

### Question: 1

By using the method of completing the square, find the roots of quadratic equations.

### Solution:

So, the roots for the given equation are: x = 3√2or x = √2.

### Question: 2

By using the method of completing the square, find the roots of quadratic equations.

2x2 7x + 3 = 0

### Solution:

2x2 - 7x + 3 = 0

x = 12/4 or x = 2/4

x = 3 or x = ½

### Question: 3

By using the method of completing the square, find the roots of quadratic equations.

3x2 + 11x + 10 = 0

### Solution:

3x2+ 11x + 10 = 0

x = (-5)/3 or x = - 2

### Question: 4

By using the method of completing the square, find the roots of quadratic equations.

2x2 + x 4 = 0

### Solution:

2x2 + x − 4 = 0

Are the two roots of the given equation.

### Question: 5

By using the method of completing the square, find the roots of quadratic equations.

2x2 + x + 4 = 0

### Solution:

2x2 + x + 4 = 0

x2 + x2 + 2 = 0

Since, √(-31)  is not a real number, Therefore, the equation doesn’t have real roots.

### Question: 6

By using the method of completing the square, find the roots of quadratic equations.

### Solution:

Therefore, x = (- √3)/2 and x = (- √3)/2. Are the real roots of the given equation.

### Question: 7

By using the method of completing the square, find the roots of quadratic equations.

### Question: 8

By using the method of completing the square, find the roots of quadratic equations.

### Question: 9

By using the method of completing the square, find the roots of quadratic equations.

### Solution:

x = √2  or  x = 1.

### Question: 10

By using the method of completing the square, find the roots of quadratic equations.

x2 - 4ax + 4a2 - b2 = 0

### Solution:

x2 - 4ax + 4a2 - b2 = 0

x- 2(2a).x + (2a)2 - b= 0

(x - 2a)2 = bx - 2a = ± b x - 2a = b or x - 2a

= - b x = 2a + b or  x = 2a - b

Therefore, x = 2a + b or  x = 2a - b are the two roots of the given equation.

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