19. If the pg", and "terms of an A. P. are a, b, and c respectively. prove that: p(b-c) + (ca) + rſa-b) = 0 50 Approved by Curriculum Development Centre​

Step-by-step explanation:a = m + (p-1)*d

b = m + (q-1)*d

c = m + (r-1)*d

p(b-c) = p*(q-r)*d

q(c-a) = q*(r-p)*d

r(a-b) = r*(p-q)*d

p(b-c)+q(c-a)+r(a-b)

= p*(q-r)*d + q*(r-p)*d +r*(p-q)*d

= (pq-pr+qr-pq+rp-qr)*d

= 0*d = 0

So i prove p(b-c)+q(c-a)+r(a-b)=0 hope this is helpfull

#15. square

step-by-step explanation:

because quadrilatural (idk how to spell it) means somthing that is not 3d or like, equal sides (or somthing like that   you know what i meanz)

hope this halps!

bai!

333.74 ! should be your answer for this question