Question

The real number k for which the equation, 2x^3+3x + k = 0 has two distinct real roots in [0,1]
(1) lies between 2 and 3
(2) lies between −1and 0
(3) does not exist
(4) lies between 1 and 2

Answer 1

@zzr0ck3r

Answer 2

Differentiate it

Answer 3

how can a cubic have two real roots? i thought it is either all real or 1real + 1 conjugate complex?

Answer 4

\[\Huge 6x^2+3 \]
6x^2=>always positive since its a square
3 can't be negative either
so I can say the slope of the graph is Continuoulsy increasing
therefore it will cut the x-axis only ONCE..

It can't cut twice,so it can never have 2 values..so option C :)

Answer 5

@yrelhan4 ?check it please

Answer 6

ok

Answer 7

do u know the answer?

Answer 8

@Math2400 Madam can you suggest some different way ?

Answer 9

@dan815

Answer 10

isn't it a question from JEE main?

Answer 11

How ?

Answer 12

nope it is correct,and my solution is perfect

Answer 13

how can a cubic expression have 2 real roots? its either 3 real, or 1 real and 2 complex.

Answer 14

yo so C

Answer 15

You all confusing me, request yo'll to give a definite solution

Answer 16

@goformit100
http://www.youtube.com/watch?v=P-RlgYTeI-8

Answer 17

sahi hai.

Answer 18

What is @yrelhan4 Saying ?

Answer 19

@goformit100 he is saying my solution is perfect

Answer 20

ok

Answer 21

What ?

Answer 22

do u understand hindi?