Elitmus
Exam
Numerical Ability
Probability
how many solutions exist for sqrt(x+5)=x(sqrt(x+5))
options are a)1 b)2 c)3 d)4
Read Solution (Total 17)
-
- x(sqrt(x+5))-sqrt(x+5)=0
(x-1)(sqrt(x+5)=0
so,
x-1=0 or x+5=0;
so,
x=1 or -5 - 10 years agoHelpfull: Yes(31) No(3)
- ans: c i.e 3
(x+5)^1/2 = x(x+5)^1/2
squaring both side
then we get
x+5 = x^2(x+5)
x+5 - x^2(x+5) = 0
take x+5 as common
x+5(1-x^2)=0
(x+5)(1+x)(1-x)=0 i.e a^2-b^2
x=-5;
x=-1;
x=1 - 10 years agoHelpfull: Yes(18) No(16)
- x=-5,-1,&1
but
x=-1 does not satisfy the eqn.
so only 2 are ans
(b) - 10 years agoHelpfull: Yes(14) No(0)
- after calculation we get x^2=1 so, x=1 or -1. so, 2 solutions exist. ans: (b)
- 10 years agoHelpfull: Yes(3) No(3)
- ans is c ie 3
- 10 years agoHelpfull: Yes(2) No(7)
- Why -1 cannot be considered? if we put x=-1 in the equation we get:
sqrt(-1+5)=-1(sqrt(-1+5))
=>sqrt(4)=-1(sqrt(4))
=>(+-)2=-1[(+-)2]
=>(+-)2=(-+)2
L.H.S.=R.H.S
Why this caanot be considered? - 10 years agoHelpfull: Yes(1) No(4)
- sqrt(x+5)=x sqrt(x+5)
square both side,
x+5=x^2 (x+5)
x^3+5x^2+x+5=0
(x^2+1)(x+5)=0
x=1,-5
x=1 - 10 years agoHelpfull: Yes(1) No(0)
- Come on guys!!! Ans is clearly 3. Let m explain in detail :
By squaring on both sides you get : x+5 = x^2(x+5)
==> x+5 = x^3 + 5(x^2)
==> (x^3) + 5(x^2) - x - 5 = 0
If you solve the above equation, we get 3 values for x i.e : +1, -1, -5 . Therefore, 3 solutions. Substitute them in the above equation, you will get the answer. - 10 years agoHelpfull: Yes(1) No(2)
- Given sqrt(x+5)=x(sqrt(x+5)),
Squaring both the sides, we get: (x+5)=x^2(x+5)
Cancelling the equal terms i.e. (x+5) from both sides, we get: 1=x^2
Now, taking the square root on both sides, we get
1=x;
which means either +1 or -1 can give 1,
Thus it has 2 roots.
Therefore , Answer is 2.
Option B is the Answer. - 6 years agoHelpfull: Yes(1) No(0)
- ans will be 3 soluton
1st direcrtly cancel sqrt(x+5) frem both side we get x=1
then bring above equestn in polynomial frm by squaring bth side
then divide it by x-1 to get further roots of x - 10 years agoHelpfull: Yes(0) No(2)
- ANSWER==> b)2
x=1/-5 - 10 years agoHelpfull: Yes(0) No(0)
- ans is 3
suaring both side..x=5,-1,1 - 10 years agoHelpfull: Yes(0) No(3)
- c-3 solutions
- 10 years agoHelpfull: Yes(0) No(2)
- sq(x+5)=xsq(x+5) : squaring x+5 = x^2(x+5)
x+5/(x+5)=X^2 , so x = +-1, so solution 2,,, - 10 years agoHelpfull: Yes(0) No(1)
- we got x= -5,-1 and 1
but put -1 in original eq:- sqrt(-1+5) =-1(sqrt(-1+5))
-> 2 = -2
so,-1 not satisfied the above equation so only two solution can be possible.
Ans: b)2 - 9 years agoHelpfull: Yes(0) No(0)
- sqrt(x+5)=x(sqrt(x+5))
squaring both sides
(x+5)=x^2(x+5)
x^2=1=>x=+/- 1
so nly 2 solution - 9 years agoHelpfull: Yes(0) No(0)
- sqrt(x+5)=x(sqrt(x+5))
Squring both side
x+5=x^3+5x
=> x^3+4x+-5=0
=>(x-1)(x^2+x+5)=0
x=1 is a solution
and (x^2+x+5)=0
D=b^2-4ac
D=1-20=-19
so there is no real solution apart from 1
Correct answer is a) 1 - 6 years agoHelpfull: Yes(0) No(0)
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