ICSE Class X Math 2015 Solved Paper

Question : 15 of 52

Marks: +1, -0

Find the value of '

K

' for which

x=3

is a solution of the quadratic equation,

(K+2) x^2-K x+6=0 .

Thus find the other root of the equation.

Solution:

Given :

(k+2) x^2-k x+6=0

Putting

x=3

(k+2) × 9-k × 3+6\;=0

9 k+18-3 k+6\;=0

6 k\;=-24

k\;=-4

Putting

k=-4

in given equation

(-4+2) x^2-(-4) x+6\;=0

-2 x^2+4 x+6\;=0

x^2-2 x-3\;=0

x^2-3 x+x-3\;=0

x(x-3)+1(x-3)\;=0

(x+1)(x-3)\;=0

x+1=0\;\;\text " or "\; x-3=0

x=-1\;\;\text " or "\; x=3

Other root of the equation,

x=-1

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