If the operation ‘ * ’ is defined by a * b = a + b –

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If the operation ‘ * ’ is defined by a * b = a + b – ab, then 5 * 7 equals

1. 12
2. –47
3. –23
4. 35

Correct Option: C

∵ a * b = a + b – ab
∴ 5 * 7 = 5 + 7 – 5 × 7 = 12 – 35
= – 23