Q) Find the value of ‘p’ for which the quadratic equation px (x – 2) + 6 = 0 has two equal roots.
Ans:
Given quadratic equation is:
px (x – 2) + 6 = 0
or we can rewrite it as, px2 – 2p x + 6 = 0
In this equation, we can see that a = p, b = – 2p and c = 6
Since it is given that the equation has two equal roots,
D = 0
or b2 – 4ac = 0
Substituting the values of a, b and c, we get:
(-2p)2 – 4(p)(6) = 0
4p2 – 24p = 0
4p(p – 6) = 0
p = 0, p = 6
Since p ≠ 0, Hence, p = 6.
Therefore, for p = 6, the given quadratic equation will have equal roots
Check: let’s put the value p = 6 in the quadratic equation and check if we get 2 equal roots:
px (x-2) + 6 = 0
6x (x-2) + 6 = 0
x (x-2) + 1 = 0
x2 – 2 x + 1 = 0
(x-1)2 = 0
It gives two equal roots of x = 1.