Question

find the value of k if 2x^2-kx+8=0

Answer 1

a=2, b=-k, c=8

Answer 2

discriminant b^2-4ac

Answer 3

how do you get k?

Answer 4

well you would need some condition if you need to use the discriminant...like

the roots are equal.... do discriminant = 0

roots are real, unequal and rational...

etc...

but looking at the problem k could be -8, -10, -17,

Answer 5

please how did you arrive at -8, -10, -17

Answer 6

well look at the factors of 8.... they are -1 and -8 then -2 and -4

this is because the middle term is -k...

so factoring

(2x -1)(x - 8) k = -17 or (2x - 8)(x -1) k = -10

(2x -2)(x - 4) k = -10 or (2x - 4)(x -2) k = -8


thats providing that the quadratic can be factored...

if not... then there are an infinite number of solutions...

thats why you need some extra information

Answer 7

really

Answer 8

can you please try using the discriminant formula

Answer 9

(-k)^2-4(2)(8)=0

Answer 10

well if you use the discriminant all you get is an expression

\[k^2 - 4 \times 2 \times 8\]

so

\[k^2 - 64\]

it can be factored... but that all...as its just an expression

Answer 11

so are you given the fact that the discriminant is equal to zero...?

Answer 12

(-k)^2 shoud equal k

Answer 13

why k^2

Answer 14

well (-k)^2 = k^2

Answer 15

its -k x -k = k^2

the negative times a negative.... thing

Answer 16

oh ok