🧠 Calculation with Variables

Recall → Understand → Calculate → Check

1️⃣ QUICK RECALL

Like terms: same variable + same power.
Add/Subtract: operate on coefficients; keep the variable.
Multiply: multiply coefficients and variables.
Substitute: Replace → Bracket → Calculate.
Bracket: multiply the outside number by EVERY term inside.
Memory: Same variable → combine | Different variable → don't combine

Examples: 3x+5x=8x | 3x+5y cannot combine | 4x×3y=12xy | 2x×3x=6x²

2️⃣ WARM-UP: LIKE OR UNLIKE?

3x and 7x

4a² and 4a

5xy and −2xy

2x and 2y

3️⃣ CALCULATION LADDER

3x + 5x = ?

9a − 4a = ?

4x × 3y = ?

2x × 5x = ?

7x + 2x − 3x = ?

3(x + 4) = ?

4️⃣ SUBSTITUTION

If x=3: 2x+5 → 2(3)+5 → 11
Memory: Replace → Bracket → Calculate

x=4: 3x+2 = ?

a=5: 2a−3 = ?

x=2,y=3: 2x+3y = ?

5️⃣ ERROR DETECTIVE 🔍

Student: 3x+4y=7xy

Student: 2(x+5)=2x+5

Student: 3x×4x=12x

6️⃣ 60-SECOND CHALLENGE ⚡

Score: 0

🏁 FINAL RECALL

1. Same variable + same power → Like terms
2. Add/Subtract → coefficients only
3. Multiply → coefficients × coefficients; variables × variables
4. Same base × → add powers
5. Substitute → Replace → Bracket → Calculate
6. Bracket → multiply every term inside