Respuesta :

√(t + u)

√(21 + 4)

√25

5

[tex]\text{Solve by plugging in:}\\\\\sqrt(21+4)\\\\\sqrt25\\\\\text{The square root of 25 is 5, since 5 multiplied by 5 makes 25}\\\\\text{So your answer would be 5}\\\\\boxed{5}[/tex]