Question

if P=6a+8b+9c,Q=2b-3a-6c,R=c-b+3a.Then find 2p-Q-3R

Answer 1

P=6a+8b+9c,
Q=2b-3a-6c,
R=c-b+3a
2p-Q-3R
=2[6a+8b+9c]-[2b-3a-6c]-3[c-b+3a]
=12a+16b+18c-2b+3a+6c-3c+3b-9a
=6a+17b+21c

Answer 2

Hello,
If:
P=6a+8b+9c; Q=2b-3a-6c;R=c-b+3a
then
2P-Q-3R
replacing the data values, we obtain:
=2(6a+8b+9c)-(2b-3a-6c)-3(c-b+3a);
=12a+16b+18c-2b+3a+6c-3c+3b-9a;
=(12+3-9)a+(16-2+3)b+(18+6-3)c;
=6a+17b+21c

Bye :-)