f(x) = 6x^2-7x+9 where x belongs to R

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20 Feb 2012 function f(x) = 6x^2-7x+9 where x belongs to R: OPtion
1) Least value of f(x) will be 7/12
2) Least value of f(x) will be 6
3) Least value of f(x) will be -7
4) Least value of f(x) will be 9
5) This function f(x) has a least value
6) Greatest value of f(x) will be 7/12
7) This function f(x) has a greatest value
8) Zero is the least value of the function
9) The least value of the function is negative
10) None of these; Correct Option: 5 Best Solution (4)

Dr.Dipin Singh 12 years AGO

f(x) = 6x^2-7x+9
for min value of x
f'(x) = 12x-7 =0
x=7/12
min value of f(x) = 6*49/144 -7*7/12 +9 = 49/24-49/12 +9 = 167/24

so f(x) has a least value.. option 5

Like? Yes (6) | No (1)

ANU YADAV 12 years AGO

this is a quadratic eq. , it does not have real roots.-b/2a is the point of minimum value i.e 7/12 and at this point the minimum value is 6.95833 i.e we need to put 7/12 in f(x).

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Pratik Goyal 12 years AGO

reason for that question is the discriminant for this equation is lees then 0
so the graph will be a open parabola and the minimum value is at its vertex that is -b/2a
that is 7/12
hence the function have a minimum value and have no maximum value

Like? Yes (2) | No (2)

Rakesh Kumar Kohli 12 years AGO

f(x) = 6x^2-7x+9
=> f'(x) = 12x - 7
f''(x) = 12, which is always positive
=> Hence The function f(x) has a least value

Like? Yes (1) | No (2)

Dimple

India

Punjab

Time: 00:01:33

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f(x) = 6x^2-7x+9 where x belongs to R

M4maths Previous Puzzles

20 Feb 2012 function