Find the values (s) of k so that the quadratic equation  3x2

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 Multiple Choice QuestionsLong Answer Type

371.

A takes 6 days less than B to do a work. If both A and B working together can do it in 4 days, how many days will B take to finish it?


 Multiple Choice QuestionsMultiple Choice Questions

372.

If 1 is a root of the equations ay2 + ay + 3 = 0 and y2 + y + b = 0, then ab equals

  • 3

  • -72

  • 6

  • -3


 Multiple Choice QuestionsLong Answer Type

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373.

Find the values (s) of k so that the quadratic equation  3x2 - 2kx + 12 = 0 has equal roots.


Given quadratic equation is  3x2 - 2kx + 12 = 0

Here  a = 3,  b = -2k,   c = 12

The quadratic equation will have equal roots if  = 0.

   b2 - 4ac = 0

Putting the values of  a, b  and  c  we get 

 

= ( -2k )2 - 4 (3) (12) = 0

 4k 2 - 144 = 0

⇒  4k 2 = 144 

 k2 = 1444 k = 36 Considering square root on both sides,     k = 36 = ± 6

Therefore, the required values of k are  6  and  -6.


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374.

Solve for x:  4x2 – 4ax + (a2 – b2) = 0


                                   OR


Solve for x:  3x2 - 6x + 2 = 0


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375.

A shopkeeper buys some books for Rs. 80. If he had bought 4 more books for the same amount, each book would have cost Rs. 1 less. Find the number of books he bought.


                                            OR


The sum of two number is 9 and the sum of their reciprocals is 12. Find the numbers.


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