If one root of the equation\(\Large{x^2-12x+3k=0}\) is the square of the other the value of \(\Large{k}\) is:-
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Parth (parthkohli):
If \(s\) and \(s^2\) are the roots then the product of roots is \(s^3\). And the product is given by \(3k\).
OpenStudy (jiteshmeghwal9):
I did this as follows:- \[\text{Ist root}= \frac{12 + \sqrt{144-12k}}{2}\]\[\text{IInd root} = \frac{12-\sqrt{144-12k}}{2}\] since larger root is the square of smaller. therefore,\[\text{Ist root}=\left( 12-\sqrt{144-12k}\over2 \right)^2\]\[\left( 12-\sqrt{144-12k}\over2 \right)^2={12+\sqrt{144-12k}\over2}\]
Parth (parthkohli):
The sum of roots is \(12\) so I can just guess that the roots are \(3\) and \(9\).
Parth (parthkohli):
So \(3k = 3\times 9\)
OpenStudy (jiteshmeghwal9):
Ans hi 9 hai
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Parth (parthkohli):
Haan because \(3k=3\cdot 9 \iff k = 9\)
OpenStudy (jiteshmeghwal9):
accha to mujhe pura thik tarke se samjho ki tumne kaise kiya
OpenStudy (jiteshmeghwal9):
samjhao*
Parth (parthkohli):
Main samjhata hoon.
\(s\) and \(s^2\) are the roots, right?
OpenStudy (jiteshmeghwal9):
right
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Parth (parthkohli):
Vieta's formula ab dekho. \(s^2 + s = 12\) (sum of roots). Toh\[s(s + 1) = 12 \iff s = 3 \iff s^2 = 9\]