Nature Formula
Posted on Tuesday, April 6th, 2010 at 3:35 pmNature Formula
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somebody please help me with nature of roots equation?
Find all possible values of k if the equation 2x^2 +kx+8 =6x has equal roots.
I tried this myself before posting it.
I equated it like: 2x^2+6x+8=0 {My problem here is I couldnt factorise it, not even the quadratic equation formula works.} Btw, I equated it to zero 'cause when roots are equal it should be zero.
ax^2+bx+c=0
to have equal roots
b^2=4ac
2x^2+kx+8=6x can be rewritten
2x^2+(k-6)x+8=0
b^2=4ac
(k-6)^2=4*2*8
k^2-12k+36=64
k^2-12k-28=0
(k-14)(k+2)=0
k=14 or k= -2
