Question

If x = 1, y = 2 and z = 5, find the value of xy + yz − zx

Answer 1

xy + yz − zx

Substituting x = 1, y = 2 and z = 5 in the given expression:
\[(1 \times 2) + (2 \times 5) - (5 \times 1) = 2 + 10 - 5\]
\[ = 7\]