Result is 13 Square the first and Square Root the second!
4^2 + SQRT(36) - 9 = 13
ANSWER: 13 Square the first and Square Root the second! 5+4-2=25, 5^2 + SQRT(4) -2= 25; 3+9-5=7, 3^2 +SQRT(9) -5=7; 6+25-3=38, 6^2 +SQRT(25) -3=38; 2+16-2=6 , 2^2 +SQRT(16) -2=16; then 4+36-9= 4^2 + SQRT(36) - 9 = 13