+309 Answer: \(3\)
There are two ways to do this.
Way 1:
The number is obviously going to be small.
Guessing 1: Left side is 36
Guessing 2: Left side is 49
Guessing 3: Left side is 64
3 is the answer.
Way 2:
Way 1 would not have worked if the number was not an integer, or if it were larger. Factoring the left side gives (x+5)², and 64 = 8². So, you have x+5=8, which gives the answer x = 3.
