# Find the values that give the function only one solution

• Mar 18th 2011, 01:35 PM
Anna55
Find the values that give the function only one solution
For which values of the constant d does the function x^2+(d-1)x+d have only one solution? State an exact answer. Thank you in advance!
• Mar 18th 2011, 01:42 PM
Plato
Quote:

Originally Posted by Anna55
For which values of the constant d does the function x^2+(d-1)x+d have only one solution? State an exact answer. Thank you in advance!

What value(s) of $d$ make the discriminant zero.
You know: $b^2-4ac=0$
• Mar 18th 2011, 02:03 PM
Anna55
I do not understand. Don't I need to know the value of a and c to make the discriminant equal zero?
• Mar 18th 2011, 02:05 PM
e^(i*pi)
$b^2-4ac$ refers to the notation used in the standard quadratic form which is $ax^2+bx+c=0$

For you $a = 1$ and $b= d-1$ and $c = d$