Latest Elitmus Aptitude Question SOLUTION: c consists of only non negative numbers in the given equation x^2 - 7x + c =0 how many rational roots occurs a.) 1 b.) 4 c.) 6 d.) infinite

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(#M40040390) ELITMUS Numerical Ability question Keep an EYE

c consists of only non negative numbers in the given equation x^2 - 7x + c =0 how many rational roots occurs
a.) 1 b.) 4 c.) 6 d.) infinite

Asked In Elitmus Pravena (9 years ago)

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Kumar Vikash  (9 years ago)

in question something is missing that is c is also real non negative numberd 49-4c for finding the value of roots of this equation (49-4c)^1/2 has to rational integerso only c=0,6,10,12 hence b)4 is correct answer.

Is this solution Helpfull? Yes (24) | No (3)  

satyam shivam  (9 years ago)

ans is d.

Is this solution Helpfull? Yes (16) | No (3)  

srinu  (9 years ago)

In question they are asking only how many rational roots and c consists only non negative numbers means whole no.s . So for c=0 , the equation has 2 roots and for c=1 there will be 2 roots and for c=2 there will be 2 roots and for c=3 there will be 2 roots and so on.
so the equation has infinite roots

Is this solution Helpfull? Yes (5) | No (5)  

sanjit kumar  (9 years ago)

for rational root D=perfect squre here D=49-4c and also we cant take c(-ve)a/c to question so possible value of c for which root is rational is C=0,6,10,12
WHERE D=b*b-4ac

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Pravena  (9 years ago)

This question was asked in yesterday elitmus test .... one of the simplest
question

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Pranshu Preet Kaur  (9 years ago)

ans is infinite

Is this solution Helpfull? Yes (2) | No (1)  

Deepak Kumar Sahu  (8 years ago)

b) 4 is the answer. Vikash is correct. I got this question yesterday in litmus.

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Nilanjana Gupta  (9 years ago)

c) 6 rational roots possible

Is this solution Helpfull? Yes (1) | No (3)  

AMIT ANAND  (9 years ago)

(49-4c)^1/2
put c=0,6,10,12 we get 2 rational roots distinct each time.
so total is 8 roots.Pravena please dont give incomplete choices.

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Pravena  (9 years ago)

there was no option as 8....

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Ehtesham  (9 years ago)

for rational roots D >=0;
(49-4c)^1/2>=0;

so probable value of c={0,1,2,3,4,5,6,7,8,9,10,11,12}

substituting these value of c one by one we will see at c={0,6,10.12}
condition gets full fill...so
Ans should be (b).

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tirupathi reddy  (9 years ago)

C is the answer
Put c=6,10,12
The roots are 1,6,2,5,3 and 4

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tirupathi reddy  (9 years ago)

Can anyone explain me why it is infinite

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Kumar Vikash  (9 years ago)

in question something is missingthat isc is also real non negative numberd49-4c for finding the value of roots of this equation49-4c12 has to rational integerso only c061012hence b4 is answer

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Pravena  (9 years ago)

@ Amit Anand The choices r not incomplete...

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Bruce  (9 years ago)

option b is right

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lalita kesarwani  (9 years ago)

there should be an additional information regarding c that what type of value shoul it take if it can take +ve real no. then answer should be 8 as c can take values : 0,6,10,12 all together which gives 8 roots otherwise answer will be d infinite

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arvind kumar sah  (9 years ago)

option d is correct

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Suyash  (9 years ago)

49-4*1*c>=0
=>c

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swati priya  (9 years ago)

there will be total of 4 value of c i.e., c=0,6,10,12 which will give rational roots
as roots= (7+-(49-4c)^1/2) /2 should be rational.

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