Giải các phương trình sau (đặt ẩn phụ):
a) ${\log }_3^{2}x+(x-12){\log }_{3}x+11-x=0$

b) $6.9^{{\log }_{2}x}+6.x^2=13.x^{{\log }_{2}6}$

c) $x.{\log }_2^{2}x-2(x+1).{\log }_{2}x+4=0$

d) ${\log }_2^{2}x+(x-1){\log }_{2}x=6-2x$

e) $(x+2){\log }_3^2(x+1)+4(x+1){\log }_3(x+1)-16=0$

f) ${\log }_{x^2}(2+x)+{\log }_{\sqrt{2-x}}x=2$

g) ${\log }_3^2(x+1)+(x-5){\log }_3(x+1)-2x+6=0$

h) $4\sqrt{{\log }_{3}x-1}-{\log }_3\sqrt{x}=4$

i) ${\log }_2(x^2+3x+2)+{\log }_2(x^2+7x+12)=3+{\log }_{2}3$