Question

what is the value of the discriminate -18x^2+5x-13=0 I have been doing this problem and I got to what I thought may be the answer but it just seems to outragious to be true

Answer 1

okay discriminant is b^2 - 4ac, so in this case b = 5, a = -18, c = -13, so 5² - 4*-18*-13 = 25-936=-911

Answer 2

Does that make sense?

Answer 3

see I came out with -982.12? I used -b/2(a) so I did -5/2(-18)= -5/-36

Answer 4

if you got anegative answer in the discriminant it has a complex roots

Answer 5

b/2a is the vertex or the min or maximum value of the quadratic equation

Answer 6

ok we use this and then take the answer and put it in the equation is what I thought

Answer 7

the vertex x=-b/(2a)=-5/(2)(-18)=5/36

Answer 8

you can plug this to the orig eq y=-18x^2+5x-13
y=-18(5/36)^2 +5(5/36)-13

Answer 9

y=-287/24 =-11.9583333

Answer 10

s0 your (x,y)=(5/36, -287/24)

Answer 11

s0 your (x,y)=(5/36, -287/24)

Answer 12

thats the vertex o max value of the equation y=-18x^2+5x-13

Answer 13

but the prob is asking for the discriminate

Answer 14

b^2 - 4ac=-911