Finding the value of k that satisfies the discrimant

Question

I am struggling to do this question

Find the valus of $k$ so that $kx^2-2+kx+x=0$ has discriminant $Δ= -24$

I tried to use the formula $b^2-4ac$ but my answer is completely wrong.

Any ideas would be much appreciated

$b^2-4ac=-24$ to see we get $$k^2+10k+25=0$$ solve this to find k — Chinnapparaj R, Oct 22 '18 at 11:24
Thanks this method produces the correct answer. However how did you get to 10k — user888469, Oct 22 '18 at 11:50
$-24=b^2-4ac$ implies $-24=(k+1)^2-4(k)(-2)=k^2+2k+1+8k$ so we get $$k^2+10k+1=-24$$ — Chinnapparaj R, Oct 22 '18 at 11:59

score 0 · Answer 1 · answered Oct 22 '18 at 11:38

0

$$kx^2-2+kx+x=0\implies kx^2+(k+1)x-2=0$$ Then solve for: $b^2-4ac=-24$ for $a=k,b=k+1,c=-2$

answered Oct 22 '18 at 11:38

John Glenn

1 Answers1