Question

If 2.5 is a root of the equation 2x^2+5x−q=0, what are the possible values of q?

Answer 1

Answer:

q = -25$10 +5 = \pm \sqrt{5^2-4*2*q} \\ 225 = 25-8q \\\\8q = -200 \rightarrow q = -\frac {200}8 = -25$

Step-by-step explanation:

Grab the generic solution of the equation. $\frac 52 = \frac{-5 \pm \sqrt{5^2-4*2*q}}{2*2}$. Let's isolate the radical, and square both sides.$10 +5 = \pm \sqrt{5^2-4*2*q} \\ 225 = 25-8q \\\\8q = -200 \rightarrow q = -\frac {200}8 = -25$

Answer 2

Answer:

since we know that x1=2.5

we can just just use vieta's theorem

x1+x2=-b/a

x1*x2=c/a