if one root of the quadratic equation kx²-3x-1=0 is 1/2 then find value of k
Answers
Answered by
36
1 / 2 is the root of the equation:
k x² - 3 x - 1 = 0
Hence 1 / 2 satisfies the value of x in the equation
So just put 1 / 2 as x in the given equation
Hence the equation becomes:
k ( 1 / 2 ) ² - 3 ( 1 / 2 ) - 1 = 0
==> k ( 1 / 4 ) - 3 / 2 - 1 =0
==> k / 4 - ( 3 + 2 ) / 2 = 0
==> k / 4 - 5 / 2 = 0
==> k / 4 = 5 / 2
==> k / 2 = 5
==> k = 5*2
==> k = 10
The value of k is 10
Hope it helps you
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kalpana26:
thank u.
thank u.
how did 3+2 come???
3+2=5
-3/2 - 1 = -1 ( 3/2 + 1 ) = -1( 3+2 )/2 = -5/2 ......3/2+1 here lcm of 2 and 1 =2 .... thats why (3+2) / 2 ...got it ?
ohhhhhh
thanks
welcome :-)
Answered by
17
Answer:
Step-by-step explanation:
k ( 1 / 2 ) ² - 3 ( 1 / 2 ) - 1 = 0
==> k ( 1 / 4 ) - 3 / 2 - 1 =0
==> k / 4 - ( 3 + 2 ) / 2 = 0
==> k / 4 - 5 / 2 = 0
==> k / 4 = 5 / 2
==> k / 2 = 5
==> k = 5*2
==> k = 10
The value of k is 10
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