Question

Solve : x^2 - 2x - 15 = 0

Method of Quadratic equation.

Answer 1

Answer:

Focal Length of Mirror = f = - 20 cm

Image Distance = v = - 60 cm

We are required to find out the object distance. Considering the mirror as Concave.

Let the object distance = u

By using Mirror Formula.

1/u + 1/v = 1/f

1/u - 1/60 = -1/20

1/u = -1/20 + 1/60

1/u = (-3 + 1)/60

u = - 60/2

\bf{u\:=-\:30\:cm}u=−30cm

Hence,

The object distance = u = -30 cm

Answer 2

Step-by-step explanation:

SOLUTION

Given :

${x}^{2} - 2x - 15 = 0$

Find :

The roots of given equation.

SO :

$= > {x}^{2} - 5x + 3x - 15 = 0$

$= > x(x - 5) + 3(x - 5) = 0$

$= > (x - 5)(x + 3) = 0$

$= > x - 5 = 0 \: \: \: or \: \: \: x + 3 = 0$

$= > x = 5 \: \: \: or \: \: \: x = - 3$

Hence :

The roots of the given equation are 5, -3.