Question

Tính:

\(\sqrt{\left(-5\right)^2}\)=?

\(\sqrt{\left(3-\sqrt{5}\right)^2}\)=?

\(\sqrt{25}\)+\(\sqrt{81}\)-5\(\sqrt{0,49}\)=?

Answer 1

\(\sqrt{\left(-5\right)^2}=\sqrt{25}=5\)

\(\sqrt{\left(3-\sqrt{5}\right)^2}=3-\sqrt{5}\)

\(\sqrt{25}+\sqrt{81}-5\sqrt{0,49}=5+9-5\cdot0,7=10,5\)

Answer 2

a)\(\sqrt{\left(-5\right)^2}=\sqrt{25}=5=-5\)

b)\(\sqrt{\left(3-\sqrt{5}\right)^2}=\sqrt{\left(3^2-2.3.\sqrt{5}+\sqrt{5}^2\right)}=\sqrt{\left(9-6.\sqrt{5}+5\right)}=\sqrt{14-\sqrt{5}}\)

c)\(\sqrt{25}+\sqrt{81}-5\sqrt{0,49}=5+9-5.0,7=14-3,5=10,5\)

Answer 3

a)\(\sqrt{\left(-5\right)^2}=\sqrt{25}=\pm5\)

b)\(\sqrt{\left(3-\sqrt{5}\right)^2}=3-\sqrt{5}\)

c)\(\sqrt{25}+\sqrt{81}-5\sqrt{0,49}=\sqrt{5^2}+\sqrt{9^2}-5\sqrt{\left(0,7\right)^2}=5+9-5\cdot0,7=10,5\)

Answer 4

\(\sqrt{\left(-5\right)^2}=\sqrt{25}=5\)

\(\sqrt{\left(3-5\right)^2}=\sqrt{\left(-2\right)^2}=\sqrt{4}=2\)

\(\sqrt{25}+\sqrt{81}-5\sqrt{0,49}=5+9-5.0,7=45-3,5=41,5\)

Answer 5

-5