Question

Answer 1

(d1): x+2y-3=0

=>x+2y=3

=>2y=-x+3

=>\(y=-\frac12x+3\)

(d2): mx+5y-m+1=0

=>mx+5y=m-1

=>5y=-mx+m-1

=>\(y=x\cdot\frac{-m}{5}+\frac{m-1}{5}\)

a: Để (d1) cắt (d2) thì \(\frac{1}{m}<>\frac25\)

=>\(m<>\frac52\)

b: Để (d1) vuông góc với (d2) thì \(\frac{-m}{5}\cdot\frac{-1}{2}=-1\)

=>\(\frac{m}{10}=-1\)

=>m=-10

c: Để (d1)//(d2) thì \(\frac{1}{m}=\frac25<>\frac{3}{m-1}\)

=>\(m=\frac52;\frac25<>\frac{3}{m-1}\)

=>m=5/2; 2/5<>3/(5/2-1)=3:3/2=2(đúng)

=>m=5/2