Question

write the answer in simplified radical form

Answer 1

Put x = 9 to the expression:

$\sqrt{21-x}\to\sqrt{21-9}=\sqrt{12}=\sqrt{4\cdot3}=\sqrt4\cdot\sqrt3=2\sqrt3$

$Used\ \sqrt{ab}=\sqrt{a}\cdot\sqrt{b}\\\\\sqrt4=2\ \text{because}\ 2^2=4$

Answer 2

Answer:

2√3

Step-by-step explanation:

subtract the numbers 21 - 9 = 12

do prime factorization 2² * 3

then apply the radical rule

√2² = 2

2√3

I hope this helps! :)