Question

Giup mik với

Answer 1

a. \(\sqrt{\left(2+\sqrt{7}\right)^2}=2+\sqrt{7}=2\dfrac{\sqrt{7}}{1}\)

c. \(5\sqrt{x^2-6x+9}=5\sqrt{\left(x-3\right)^2}=5\left(x-3\right)=5x-15\)

d. \(\sqrt{\left(2-\sqrt{5}\right)^2}+\sqrt{\left(\sqrt{5}-7\right)^2}=2-\sqrt{5}+\sqrt{5}-7=-5\)

Answer 2

a) \(\sqrt{\left(2+\sqrt{7}\right)^2}=\left|2+\sqrt{7}\right|=2+\sqrt{7}\)

b) \(\sqrt{4+2\sqrt{3}}=\sqrt{\left(\sqrt{3}+1\right)^2}=\sqrt{3}+1\)

c) \(5\sqrt{x^2-6x+9}=5\sqrt{\left(x-3\right)^2}=5\left|x-3\right|=5\left(3-x\right)=15-5x\)(do x<3)

d) \(\sqrt{\left(2-\sqrt{5}\right)^2}+\sqrt{\left(\sqrt{5}-7\right)^2}=2-\sqrt{5}+\sqrt{5}-7=-5\)

Answer 3

b: \(\sqrt{4+2\sqrt{3}}=\sqrt{3}+1\)