Đáp án:
$D=-a\\ E=6a^2\\ F=-5a^3\\ G=x-1\\ H=x+2\\ M=1$
Giải thích các bước giải:
$D=2\sqrt{a^2}-3a (a \ge 0)\\ =2|a|-3a\\ =2a-3a\\ =-a\\ E=\sqrt{a^4}+5a^2\\ =\sqrt{(a^2)^2}+5a^2\\ =a^2+5a^2\\ =6a^2\\ F=3\sqrt{a^6}-2a^3(a <0)\\ =3\sqrt{(a^3)^2}-2a^3\\ =3|a^3|-2a^3\\ =-3a^3-2a^3\\ =-5a^3\\ G=\sqrt{x^2-2x+1} ( x \ge 1)\\ =\sqrt{(x-1)^2} ( x \ge 1)\\ =|x-1|\\ =x-1\\ H=\sqrt{x^2+4x+4}(x > -2)\\ =\sqrt{(x+2)^2}\\ =|x+2|\\ =x+2\\ M=\sqrt{9-6x+x^2}.\dfrac{1}{x-3} ( x >3)\\ =\sqrt{(x-3)^2}.\dfrac{1}{x-3}\\ =|x-3|.\dfrac{1}{x-3}\\ =(x-3).\dfrac{1}{x-3}\\ =1$
