Mn làm giúp mik với , làm đúng , đủ bước thì mik vote 5 sao và câu trả lời hay nhất ạ

a, $A=\sqrt{16-6\sqrt 7}\\=\sqrt{9-6\sqrt 7+7}\\=\sqrt{(3-\sqrt 7)^2}\\=|3-\sqrt 7|\\=3-\sqrt 7$

b, $B=\sqrt{29-12\sqrt 5}\\=\sqrt{20-2.2\sqrt 5.3+9}\\=\sqrt{(2\sqrt 5-3)^2}\\=|2\sqrt 5-3|\\=2\sqrt 5-3$

c, $C=\sqrt{9+4\sqrt 5}-\sqrt{9-4\sqrt 5}\\=\sqrt{5+4\sqrt 5+4}-\sqrt{5-4\sqrt 5+4}\\=\sqrt{(\sqrt 5+2)^2}-\sqrt{(\sqrt 5-2)^2}\\=|\sqrt 5+2|-|\sqrt 5-2|\\=\sqrt 5+2-\sqrt 5+2\\=4$

d, $D=\sqrt{17+12\sqrt 2}+\sqrt{17-12\sqrt 2}\\=\sqrt{9+2.3.2\sqrt 2+8}+\sqrt{9-2.3.2\sqrt 2+8}\\=\sqrt{(3+2\sqrt 2)^2}+\sqrt{(3-2\sqrt 2)^2}\\=|3+2\sqrt 2|+|3-2\sqrt 2|\\=3+2\sqrt 2+3-2\sqrt 2\\=6$

e, $E=\sqrt{28+10\sqrt 3}-\sqrt{4-2\sqrt 3}\\=\sqrt{25+2.5.\sqrt 3+3}-\sqrt{3-2\sqrt 3+1}\\=\sqrt{(5+\sqrt 3)^2}-\sqrt{(\sqrt 3-1)^2}\\=|5+\sqrt 3|-|\sqrt 3-1|\\=5+\sqrt 3-\sqrt 3+1\\=6$

f, $F=\sqrt{x^2-x+\dfrac{1}{4}}-2x\\=\sqrt{\bigg(x-\dfrac{1}{2}\bigg)^2}-2x\\=\bigg|x-\dfrac{1}{2}\bigg|-2x\\=x-\dfrac{1}{2}-2x(do\,\,x\ge \dfrac{1}{2})\\=-x-\dfrac{1}{2}$