How many terms are there in the expansion of (y⁴ − 2 + 1/y⁴)⁴?

Correct answer: c 9

(y⁴ − 2 + 1/y⁴) = (y² − 1/y²)², so the expression is (y² − 1/y²)⁸ with 8 + 1 = 9 terms, so this is the value.

Why the other options are wrong

• a 5: 5 would be right for power 4; the power is actually 8. The right answer is 9.
• b 8: 8 is the power, not the number of terms. The right answer is 9.
• d 16: 16 comes from 4 × 4; the number of terms is the power plus 1. The right answer is 9.