Question

Evaluate:

(−1) × (−1) × (−1) × (−1) × ...70 times

Answer 1

(−1) × (−1) × (−1) × (−1) × ...70 times

Group in pairs

(−1) × (−1) = 1

Each pair of (−1) multiplies to 1. Since there are 70 instances of (−1), we can divide 70 into 35 pairs.

Each of the 35 pairs results in 1. Hence, the entire product is:

1 × 1 × 1 …(35 times) = 1

= 1