posted by toni .
Im lost i don't know how to do this can someone show me step by step how to solve this
For what value of c does the equation have one real root? Hint using the values of a and b found in the equation, solve D = 0 for c.
Consider the quadratic expression X^2 + 4x + c = 0.
Recall the formula for discriminant. For a quadratic equation in the general form, ax^2 + bx + c = 0,
D = b^2 - 4ac
D = 0 : real, equal/double root
D > 0 : two real, unequal roots
D < 0 : two imaginary roots
Since we're required to have one real root, we equate D to zero, and solve for the unknown, c.
x^2 + 4x + c = 0
a = 1
b = 4
c = ?
Substituting to the discriminant formula, (D = 0)
0 = 4^2 - 4*1*c
0 = 16 - 4c
4c = 16
c = 4
Hope this helps~ :3