Question

For what value of k, x² - 4x + k touches x-axis.​

Answer 1

Answer:

The answer to this question is 4

Step-by-step explanation:

The given equation will touch the x-axis when the discriminant of the given equation is zero$\text{We Know that the discriminant of a quadratic equation of the form } ax^2+bx+c = 0\text{ is }D = b^2 - 4ac\\ or,D = (-4)^2 - 4(1)(k)~~(\because\text{ for the given equation } a=1,b=-4\text{ and } c=k~)\\or, D = 16 - 4k$

The condition for which the given equation touches the x-axis is $D =0$

or, 16-4k = 0

or, 4k = 16

or,k = 4

Answer 2

Step-by-step explanation:

D=(-4)^2-4(1)

The condition for which the given equation touches the x-axis D=0

or,16-4k=0

4k=16

k=16/4

k=4