/ Class 9 · Chapter 7: Indices [Exponents] Function Lab

Simplify: Nested Powers

Master the order: expand brackets, multiply, then divide.

Equation
y = (1*x^5)^2 / x^8
Graph
12345-20M20M60M100M140M180Mg2xy
Table
xy
11
24
39
416
525

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Selina ICSE: Indices [Exponents]

What this lesson covers

What you do

You shape the function y = (k*x^5)^2 / x^m and watch the graph answer.

Challenges to clear

  • Set k = 2 and slide m to 10: at x = 2, (2·32)² / 2¹⁰ = 4096/1024 = 4.
  • The curve goes FLAT at 4: x = 3 gives 4 too — every x cancelled.
  • A fourth power inside the bracket now. Set the coefficient k to 3.
  • Squaring gives x⁸ on top. Slide m until the curve goes FLAT at 9 — every x has cancelled, leaving just k².

Check yourself

Why does the expression (2 * x^5)^2 / x^10 always equal 4, regardless of the value of x?

In the step (2 * x^5)^2, why does the coefficient 2 become 4?

  • Because (2*x^5)^2 becomes 4*x^10, and x^10 divided by x^10 is 1, leaving only 4. — correct
  • Because x^10 in the denominator cancels out the 2 in the numerator.
  • Because squaring x^5 makes it x^10, which is larger than the denominator, so it grows.
  • Because 2 squared is 4, and the x terms are ignored in division.
  • The exponent applies to every factor inside the parentheses, so 2^2 = 4. — correct
  • The exponent only applies to the variable x, not the number 2.
  • It is a special rule that coefficients double when squared.
  • The 2 is added to the exponent 5, resulting in 7, then squared.

Think about it

  • (2x⁵)² = 4x¹⁰. Dividing by x^m — what m kills ALL the x's?
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