Q- what is the value of k if the equation 9x2+2kx-1=0 has real roots ?
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9x^2+2kx-1=0
When real roots, the discriminant is greater than zero.
D=0
b^2-4ac=0
(2k)^2-4X9X-1=0
4k^2+36=0
4k^2= -36
k^2= -36/4
k^2= -9
k^2+9=0
Since square of any number is positive , therefore above expression is positive for any value of k.
When real roots, the discriminant is greater than zero.
D=0
b^2-4ac=0
(2k)^2-4X9X-1=0
4k^2+36=0
4k^2= -36
k^2= -36/4
k^2= -9
k^2+9=0
Since square of any number is positive , therefore above expression is positive for any value of k.
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