/ Class 7 · Chapter 13: Fundamental Concepts Function Lab

Multiply Monomials: The 3-Variable Swap

See how coefficients multiply and variables group when expanding a product.

Equation
y = (1*x^2) * (1*x)
Graph
0123404008001.2k1.6kg2xy
Table
xy
00
11
28
327
464

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Selina ICSE: Fundamental Concepts

What this lesson covers

What you do

You shape the function y = (a*x^2) * (b*x) and watch the graph answer.

Challenges to clear

  • Build (2x^2)(3x): set a = 2 and b = 3. At x = 2 you should see 48 — that is 6x^3 = 6 × 8.
  • Check the coefficient alone: at x = 1 the product is just a × b = 6.
  • Higher powers now: (a x³)(b x²). Set a = 2.
  • Slide b until x = 2 reads 256. Powers ADD to give x⁵, coefficients MULTIPLY — 8 × 32 = 256.

Check yourself

Why must the variable base (x) be the same to add the exponents?

Evaluate (2x^2) * (3x^4) using the law.

  • Because exponent laws only apply when bases are identical; otherwise, you cannot combine them into a single power. — correct
  • Because adding exponents is the same as multiplying bases.
  • Because different variables represent different quantities that cannot be mathematically combined.
  • Because the coefficients a and b determine if the exponents can be added.
  • 6x^6 — correct
  • 5x^6
  • 6x^8
  • 5x^8

Think about it

  • (2x^2)(3x) groups as (2×3) × (x^2 · x). What are the new coefficient and exponent?
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