O Level MathematicsC2.1 Introduction to algebra (substitution).

🔢 Substitution Made Simple!

Edudent Academy
10 Dec 25

Algebra lets us describe patterns and solve real-world problems efficiently. A core skill is *substitution*—replacing letters with numbers. Mastering it means you can turn abstract symbols into concrete answers, a must for scoring well in O-Level exams!

Key Concept: Substitution

To substitute, **identify the variable**, **insert the given value**, and **simplify carefully**, following order of operations. For example, substituting x=3x=3 in 2x+52x+5 gives 2(3)+5=112(3)+5=11.

Worked Example: Evaluate 5p−2q5p-2q

  • Problem: Find the value of 5p−2q5p-2q when p=4p=4 and q=−3q=-3.
  • Step 1:
    5(4)−2(−3)5(4)-2(-3)
  • Step 2:
    20+6=2620+6=26
  • Answer:
    2626
    . Keep practising with fresh numbers to make substitution second nature!