Question

Roy exclaims that his quadratic with a discriminant of -9 has no real solutions. Roy then puts down his pencil and refuses to do any work. Create an equation with a negative discriminant. Then explain to Roy how to find the solutions even if they are not real

Answer 1

@ganeshie8 maybe you could help on this one?

Answer 2

@TheHero @Frostbite @emilyhaddad @wolfe8

Answer 3

First, recall how you calculate the discriminant from an quadratic equation in the general form.

Answer 4

Hmm .is it the b^2 -4ac

Answer 5

Correct. So now you just need to put in some arbitrary numbers for a, b, and c so that it is turns out negative.

Answer 6

lemme see

Answer 7

-8^2 - 4 (2)(9)

Answer 8

64 - 4 (18)

Answer 9

64 - 72

Answer 10

-8

Answer 11

Right. So now you have values for a,b, and c. Put them into the general form of a quadratic equation.

Answer 12

2x^2 - 8x +9

Answer 13

right?

Answer 14

oh wait +8

Answer 15

Well you chose -8 to be your b. So it would be a minus.

Answer 16

cause thats the formula

Answer 17

Oh wait

Answer 18

The formula for discriminant is b^2-4ac

Answer 19

lol sorry Yes you're right!

Answer 20

Right. So your first equation was correct. Now to solve it, you will have to use the formula for roots. Remember that?

Answer 21

hmm no?

Answer 22

http://www.mathwarehouse.com/quadratic/solve-quadratic-equation.php This should help. So since you have no real roots, you will have to use the formula.

Answer 23

Oh thank you!. But thats what it was asking for..for it to be imaginary lol

Answer 24

Right. So you will have to solve it using the formula. The question wants you to create an equation and solve it, basically. Good luck. I have to go get lunch now.

Answer 25

oh ok thanks