Nature of Roots of Quadratic Equation:
CBSE Ncert Solutions Chapter 4 Quadratic Equations Exercise 4.4 Q2 Download this solution
2. Find the value of k for each of the following quadratic equations, so that they have two equal roots.
(i)
(ii)
Solution (i)
We know that quadratic equation has two equal roots only when the value of discriminant is equal to zero.
Comparing equation
with general quadratic equation
, we get
and
.
Discriminant =
Putting discriminant equal to zero, we get
Solution (ii)
Comparing quadratic equation,
with general form
, we get
and
.
Discriminant =
We know that two roots of quadratic equation are equal only if discriminant is equal to zero.
Putting discriminant equal to zero, we get
The basic definition of quadratic equation says that quadratic equation is the equation of the form
, where
. Therefore, in equation
, we cannot have k =0. Therefore, we discard k=0.
Therefore, k=6
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