Question

If one of the roots of the equation x² – 4x + k = 0 exceeds the other by 2, then find the roots and determine the value of k.

Answer 1

Answer:

The roots are 1 and 3.

k = 3.

Step- by-step explanation:

We use the facts that if α and β are the roots of ax^2 + bx + c = o then α+ β = -b/a and  α β = c/a.

The roots are written as  α and α+2, then:

α + α + 2 = -(-4)

2α + 2 = 4

α + 1 = 2

α = 1

also

α (α + 2) = k

Substituting for α:

1(1 + 2) = k

k = 3.

The roots are 1 and 1 + 2 = 3.

Answer 2

Step-by-step explanation:

the solutions for a quadratic equation is

x = (-b ± sqrt(b² - 4ac))/(2a)

in our case

a = 1

b = -4

c = k

x = (4 ± sqrt(16 - 4k))/2 = 2 ± sqrt(4 - k)

x1 = 2 + sqrt(4 - k)

x2 = 2 - sqrt (4 - k)

x1 = 2 + x2

2 + sqrt(4 - k) = 2 + 2 - sqrt(4 - k)

2×sqrt(4 - k) = 2

sqrt(4 - k) = 1

4 - k = 1

k = 4 - 1 = 3

x1 = 3

x2 = 1