Answer: Let point (−2,3,5),(1,2,3)and(7,0,−1) be denoted by P , Q , and R respectively. by using distance formula d= (x 2 −x 1 ) 2 +(y 2 −y 1 ) 2 +(z 1 −z 1 ) 2 Point P,Q and R are collinear if they lie on a line. PQ= (1+2) 2 +(2−3) 2 +(3−5) 2 = (3) 2 +(−1) 2 +(−2) 2 = 9+1+4 = 14 QR= (7−1) 2 +(0−2) 2 +(−1−3) 2 = (6) 2 0 Reply

Answer:Let point (−2,3,5),(1,2,3)and(7,0,−1) be denoted by P , Q , and R respectively.

by using distance formula d=

(x

2

−x

1

)

2

+(y

2

−y

1

)

2

+(z

1

−z

1

)

2

Point P,Q and R are collinear if they lie on a line.

PQ=

(1+2)

2

+(2−3)

2

+(3−5)

2

=

(3)

2

+(−1)

2

+(−2)

2

=

9+1+4

=

14

QR=

(7−1)

2

+(0−2)

2

+(−1−3)

2

=

(6)

2

0

Answer:do it by modulas formula it is easy