Question

If p = −2, q = −1 and r = 3, find the value of p³ + q³ + r³ + 3pqr

Answer 1

p³ + q³ + r³ + 3pqr

Substituting p = -2, q = -1 and r = 3 in the given expression:

\[( - 2 )^3 + ( - 1 )^3 + (3 )^3 + 3 \times ( - 2 \times - 1 \times 3)\]
\[ = ( - 2 \times - 2 \times - 2) + ( - 1 \times - 1 \times - 1) + (3 \times 3 \times 3) + 3 \times (6)\]
\[ = ( - 8) + ( - 1) + (27) + 18\]
\[ = 36\]