英文平行線及垂直線分點數學題(20分)

11
we get C-M-D CM:MD=1:1
C(2b-1,-5),M(-1,b),D(7,c) find b,c
-2=2b-1+7 ==>2b=-8 ==>b= - 4
2b= - 8=-5+c ==>c= - 3
so b=- 4 ,c= - 3

13
Q-X-P QX:XP=3:2
Q(-5,-8),X(1,-2) ,P=?
set P(a,b)
1=2/5*(-5)+3/5*a ==>5=-10+3a ==>a=5
-2=2/5*(-8)+3/5*b ==>-10=-16+3b ==>b=2
so a=5,b=2