Math Problem Statement

Functions

Exponential functions

Adapted from DBE Nov 2015 Grade 11, P1, Q5 Maths formulas

Given:

g(x)=−2(2−x)−2g(x)=−2(2−x)−2

Determine the coordinates of the yy-intercept of gg.

INSTRUCTION: Enter your answer as a coordinate, with the values inside brackets and separated by a semicolon e.g. (x; y).

**Answer:**Coordinates of yy-intercept:

Solution

To determine the coordinates of the yy-intercept of the function g(x)=2(2x)2g(x) = -2(2^{-x}) - 2, we need to evaluate the function when x=0x = 0. The yy-intercept occurs where the graph crosses the yy-axis, which corresponds to x=0x = 0.

Substitute x=0x = 0 into the function:

g(0)=2(20)2g(0) = -2(2^{-0}) - 2

Since 20=20=12^{-0} = 2^0 = 1, the equation simplifies to:

g(0)=2(1)2=22=4g(0) = -2(1) - 2 = -2 - 2 = -4

Thus, the coordinates of the yy-intercept are:

Coordinates of y-intercept: (0;4)\text{Coordinates of } y\text{-intercept: } (0; -4)

Would you like more details, or do you have any questions?

Here are 5 related questions:

  1. How would you find the xx-intercept of the function g(x)g(x)?
  2. What does the yy-intercept represent in the context of the graph of g(x)g(x)?
  3. How would the yy-intercept change if the function were g(x)=2(2x)+3g(x) = -2(2^{-x}) + 3?
  4. How can you verify the yy-intercept graphically using a plot of g(x)g(x)?
  5. What is the effect of the negative sign in front of the exponential term on the graph of g(x)g(x)?

Tip: When calculating intercepts, substitute either x=0x = 0 for the yy-intercept or y=0y = 0 for the xx-intercept and solve the resulting equation.

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Math Problem Analysis

Mathematical Concepts

Exponential Functions

Formulas

Exponential function: g(x) = -2(2^{-x}) - 2

Theorems

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Suitable Grade Level

Grade 11