If (x + 4)(3x + 1) = 3x^2 + x, what is a possible value of x?

Question

(A) 1
(B) 1/2
(C) 1/3
(D) -1/3
(E) -1/2

Kudos for a correct  solution .

KS15 · Answer

3x^2+x+12x+4=3x^2+x
12x+4=0
x=-1/3
Answer D

kunal555 · Answer

(x+4)(3x+1) = 3x^2+x

=> 3x^2 + x + 12x +4 = 3x^2 + x
=> 12x+4 = 0
=> 12x = -4
=> x=-1/3

Answer:- D

reto · Answer

Expand the expression: (x + 4)(3x + 1) = 3x^2 + x to:

3x^2+x+12x+4 = 3x^2 +x , subtract 3x^2 from both sides
13x + 4 = x
12x = -4
x = -1/3

Answer D

GMATinsight · Answer

Rearranging the given expression:
(x + 4)(3x + 1) = 3x^2 + x
i.e. 3x^2 + 13x + 4 = 3x^2 + x
i.e. 12x = -4
i.e. x = -4/12 = -1/3

Answer: Option D

Had it been a difficult expression to solve further, then we could have used options to check which on esatisfies the expression after solving it as further as possible

AbdurRakib · Answer

Simplifying this equation is my approach here

The equation is

(x + 4)(3x + 1) = 3x^2 + x

or,3x^2 +x +12x +4=3x^2 +x
or,12x=-4
or,x=-4/12
or,x=-1/3

So the  Correct answer is D

I5O · Answer

Hi, Bunuel!
I solved this problem differently, but not sure if it's mathematically right:
(x + 4)(3x + 1) = 3x^2+ x
(x+4)(3x + 1)=x(3x+1)
(x+4)(3x+1)-x(3x+1)=0
(x+4-x)(3x+1)=0
so, first bracket is invalid, but second 3x=-1 gives the right answer x=-1/3.
What do you think :?:

ENGRTOMBA2018 · Answer

This is correct. There is no such thing as "so, first bracket is invalid".

Once you get (x+4-x)(3x+1)=0 ---> (4)(3x+1)=0 ---> means that the product of 4 and 3x+1 is =0 ---> This can only happen if either one of them or both of them are zero.

Both can not be zero as one of it is already 4. Thus, it must be then that (3x+1)=0 ---> x=-1/3

Hope this helps.

rhine29388 · Answer

(x+4)(3x+1)=3x^2+x 
simplifying the given expression
 3x^2+13x+4=3x^2+x 
12x=-4
x= \frac{-1}{3} 
correct answer option D

preetamsaha · Answer

If (x + 4)(3x + 1) = 3x^2 + x, what is a possible value of x?

(x + 4)(3x + 1) = 3x^2 + x
or,3x^2 +x +12x +4=3x^2 +x
or,12x=-4
or,x=-4/12
or,x=-1/3

correct answer D

bumpbot · Answer

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If (x + 4)(3x + 1) = 3x^2 + x, what is a possible value of x?

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If (x + 4)(3x + 1) = 3x^2 + x, what is a possible value of x?

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