Question

I reallly really need help on this please ://
ill give out a medal, best answer and ill be a fan of you :c just need some help on this question.

Answer 1

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 more work. Create an equation with a negative discriminant. Then explain to Roy, in calm and complete sentences, how to find the solutions, even though they are not real.

Answer 2

A negative discriminant has no zeroes. So a quadratic like x^2 + x + 1, which is always above the x-axis, would have no zeroes, so a negative discriminant.

This can still be solved with the quadratic formula. The square root of, in your example, -9 is 3i. You will get a valid root, but it will be complex (a+bi) form.

Answer 3

omg im so confused. ok so how would i write the equation? :/

Answer 4

Well, in order to write the equation, the entire curve needs to be above or below the x-axis. If it crosses, it has a real root. So, pick values of a, b, and c (to make it easy, let a=1) where b^2 - 4ac <0. For example, 4^2-4(1)(5) = -4. Here, a=1, b=4, and c=5. So your quadratic would be x^2+4x+5.

Does that make sense?

Answer 5

yes a little bit

Answer 6

ok so using that example how would i find the solution?

Answer 7

So, use the quadratic formula.
\[x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}=\frac{-4 \pm \sqrt{4^2-(4)(1)(5)}}{2(1)}=\frac{-4 \pm \sqrt{-4}}{2}=-2 \pm i\]

Answer 8

okok than you soo much! i get it, you really are a life savor. do you think you can help me understand two more questions? im a bit stuck and i cant move on till i finish them :/

Answer 9

Sure!