.
You are given
= 5. (1)
Square both sides. Then the very first square root sign goes away, and you get
y +
= 25. (2)
In the left side, the second addend is equal to 5, again (!)
So, your equation (2) takes the form
y + 5 = 25. (3).
From (3), you momentarily get
y = 25 - 5 = 20.
ANSWER. y = 20.
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It is not a joke. It is the standard way to solve such problems.
CHECK. Consider this sequence
= 4.472...
= 4.947...
= 4.995...
You see the sequence, which, OBVIOUSLY, converges, and converges to the value of 5.
/\/\/\/\/\/\/\/
Yes, it is a TRICK. Focus - pocus, which you can learn only from a Math circle or
from reading special books, developing Math skills for young lovers of Math.
So, today it is as if you visited a Math circle . . .
Come again soon to this forum to learn something new (!)
To see some other similar or close Math problems, look into the lesson
- Evaluating expressions that contain infinitely many square roots
in this site.