JAMB Mathematics · Section I
Study notes for Binary Operations: — part of the JAMB UTME Mathematics syllabus. 2 learning objectives with explanations and exam tips.
Think of binary operations as rules for combining two numbers. Commutativity means the order doesn't matter—just like adding 5 + 3 gives 12, and 3 + 5 also gives 8. However, subtraction fails this test since 5 − 3 ≠ 3 − 5. Associativity means when combining three numbers, grouping doesn't change your answer. For instance, (2 + 3) + 4 equals 2 + (3 + 4), both equalling 9.
Distributivity connects two operations together. Multiplication distributes over addition: 3 × (2 + 5) equals (3 × 2) + (3 × 5), which is 21. Consider sharing money with friends—if you give each person ₦3 and then ₦2, that's the same as giving each person ₦5 total.
Think of binary operations as special mathematical rules that combine two numbers. The identity element is like the "do-nothing" number—when you combine any number with it using the operation, you get back your original number. For example, in addition, zero is the identity because any number plus zero equals itself.
The inverse element is the opposite player. For any number, its inverse is what you combine with it to get the identity element back. In addition, if your number is 5, its inverse is negative 5, because 5 + (–5) = 0, the identity.
Consider sharing money in a market: if you have ₦100 and add ₦0, you still have ₦100. But if you spend ₦100 (the inverse), you return to zero naira.
Understanding which element is identity and which is inverse helps you solve equations quickly.