cho △abc ad la phan giac (d∈ bc) biet ab=3 ,ac=6 ,bd =4 tinh cd

giup minh di cam on moi nguoi nhieu 

giai cac phuong trinh sau 

a, (3x-1)(4x-8)=0

b,(x-2)(1-3x)=0

c,(x-3)(x+4)-(x-3)(2x-1)=0

d,(x+1)(x+2)=2x(x+2)

giai nhung phuong trinh sau 

3(x-2)+4=5x-2(x-1)

2(x-2)-3(1-2x)=5