Latest CAT Aptitude Question SOLUTION: One root of x2 +kx – 8 = 0 is square of the other, then, the value of k is- Options: 2,8,-8,-2

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(#M40165899) CAT Numerical Ability question Maths Keep an EYE

One root of x2 +kx – 8 = 0 is square of the other, then, the value of k is-
Options:

2,8,-8,-2

Asked In CAT Meghal Gupta (5 years ago)

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Read Solution (2) :

JAi  (5 years ago)

a,a^2 two roots
Then a+a^2=-b/a (b=k and a=1 )
a+a^2=-k (1)
we also know products of root
a*a^2=c/a. (c=-8 and a=1)
a^3=-8
a=-2. (2)
Put 2nd in 1st we get
a+a^2=-k
-2+(-2)^2=-k
-2+4=-k
K=-2. (Ans)

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Mitali Sinha  (5 years ago)

Let one root be a then another one will be a².
a+a²=-b÷a=-k
a*a²=c÷a=_8
a³=_8=_2
_2+(-2)²=_k
K=-2

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