Question

ko dùng máy tính bỏ túi

Answer 1

bài 3 mn nhé

 

Answer 2

3.

a)\(4\sqrt{x^2}\left(x< 0\right)\)

\(=4\left|x\right|=-4x\)

b)\(\sqrt{9x^2}-4x\left(x\ge0\right)\)

\(=\left|3x\right|-4x=3x-4x=-x\)

c)\(\sqrt{x^2-6x+9}+x+3\left(x\ge3\right)\)

\(=\sqrt{\left(x-3\right)^2}+x+3\\ =\left|x-3\right|+x+3\\ =x-3+x+3=2x\)

d)\(\dfrac{3+\sqrt{a}}{a-9}\left(a\ge0;a\ne9\right)\)

\(=\dfrac{\sqrt{a}+3}{\left(\sqrt{a}+3\right)\left(\sqrt{a}-3\right)}=\dfrac{1}{\sqrt{a}-3}\)

Tick nha