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I agree with @greenestamps regarding English in this post.
So, the problem, as it is worded, deserves to be rejected.
But  I  made a  SUPER-effort.  Brilliant idea came to my mind,  and  I  guessed its hidden meaning.
It is to say
    Bob's age 4 years ago  is numerically the same 
    as the square root of his age two years from now.
In this formulation, we write this equation
    x - 4 =  .
Then we square both sides
    x^2 - 8x + 16 = x + 2
and simplify it
    x^2 - 9x + 14 = 0
    (x-7)*(x-2) = 0.
Of the two roots,  x= 7  and  x= 2,  the smaller root does not work (due to obvious reason: it is too small), and we reject it.
The greater root, x= 7, works and gives the ANSWER:  Bob is 7 years old now.
.
Then we square both sides
    x^2 - 8x + 16 = x + 2
and simplify it
    x^2 - 9x + 14 = 0
    (x-7)*(x-2) = 0.
Of the two roots,  x= 7  and  x= 2,  the smaller root does not work (due to obvious reason: it is too small), and we reject it.
The greater root, x= 7, works and gives the ANSWER:  Bob is 7 years old now.
Solved.