NCERT Solutions
Class 10 Maths
Quadratic Equations

Ex. 4.3 Q1
Find the nature of the roots of the following quadratic equations. If the real roots exist, find them:
(i) 2x2 – 3x + 5 = 0
(ii) 3x2 – 4√3x + 4 = 0
(iii) 2x2 – 6x + 3 = 0
(i) 2x2 – 3x + 5 = 0
Comparing the given quadratic equation with ax2 + bx + c = 0, we have:
a = 2, b= – 3, c = 5
Now discriminant = b2 – 4ac
= (-3) 2 – 4 * 2 * 5
= 9 – 40
= -31 < 0
Since b2 – 4ac is negative.
Hence, the given quadratic equation has no real roots.
(ii) 3x2 – 4√3x + 4 = 0
Comparing the given quadratic equation with ax2 + bx + c = 0, we have:
a = 3, b= -4√3, c = 4
Now discriminant = b2 – 4ac
= (-4√3) 2 – 4* 3 * 4
= 48 – 48
= 0
Thus, the given quadratic equation has two real roots which are equal.
Here, the roots are: -b/2a and –b/2a
i.e -(-4√3)/(2 * 3) and -(-4√3)/(2 * 3)
=> 4√3/6 and 4√3/6
=> 2√3/3 and 2√3/3
=> 2√3/(√3 * √3) and 2√3/(√3 * √3)
=> 2/√3 and 2/√3
(iii) 2x2 – 6x + 3 = 0
Comparing the given quadratic equation with ax2 + bx + c = 0, we have:
a = 2, b= -6, c = 3
Now discriminant = b2 – 4ac
= (-6) 2 – 4* 2 * 3
= 36 – 24
= 12 > 0
Thus, the given quadratic equation has two real and distinct roots which are given as:
x = {-b ± √(b2 – 4 * a * c)}/2a
=> x = [-(-6) ± √{(-6)2 – 4 * 2 * 3)}]/(2 * 2)
=> x = {6 ± √(36 – 24)}/4
=> x = (6 ± √12)/4
=> x = (6 ± 2√3)/4
=> x = 2(3 ± √3)/4
=> x = (3 ± √3)/2
Thus, the roots are: (3 + √3)/2 and (3 - √3)/2