Question

Y= x^2 -2x -3 find the values of x when y=1

Answer 1

x = 1 +sqrt(5)

x = 1 -sqrt(5)

Explanation:

y= x^2 -2x -3

Let y = 1

1= x^2 -2x -3

Subtract 1 from each side

1-1= x^2 -2x -3-1

0 = x^2 -2x -4

Using the quadratic formula

x = - (-2) ±sqrt( (-2) ^2 -4(1)(-4))

----------------------------------------

2(1)

x = 2 ±sqrt( 4 +16)

------------------------

2

x = 2 ±sqrt( 20)

------------------------

2

x = 2 ±sqrt( 4*5)

------------------------

2

x = 2 ±sqrt(5)

------------------------

2

x = 1 ±sqrt(5)