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8.03 Differentiation from first principles

Interactive practice questions

Consider the function $f\left(x\right)=x^3$f(x)=x3

a

By filling in the table of values, complete the limiting chord process for $f\left(x\right)=x^3$f(x)=x3 at the point $x=3$x=3.

$a$a $b$b $h=b-a$h=ba

$\frac{f\left(b\right)-f\left(a\right)}{b-a}$f(b)f(a)ba

$3$3 $3.5$3.5 $0.5$0.5 $\editable{}$
$3$3 $3.1$3.1 $\editable{}$ $\editable{}$
$3$3 $3.05$3.05 $\editable{}$ $\editable{}$
$3$3 $3.01$3.01 $\editable{}$ $\editable{}$
$3$3 $3.001$3.001 $\editable{}$ $\editable{}$
$3$3 $3.0001$3.0001 $\editable{}$ $\editable{}$

Provide answers up to four decimal places when required.

b

The limiting chord process has been used to calculate the instantaneous rate of change for each value of $x$x given in the table. Complete the missing values.

$x$x $1$1 $2$2 $3$3 $4$4 $5$5

Instantaneous rate of change of $f\left(x\right)$f(x) at $x$x.

$3$3 $12$12 $\editable{}$ $48$48 $\editable{}$
c

We can therefore deduce that the instantaneous rate of change of $f\left(x\right)$f(x) at any point $x$x is:

Easy
8min

Consider the function $f\left(x\right)=x^2$f(x)=x2

Easy
6min

Consider the function $f\left(x\right)=2x^2$f(x)=2x2

Easy
9min

Consider the function $f\left(x\right)=3x+2$f(x)=3x+2.

Easy
2min
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Outcomes

2.4.1.1

explore average and instantaneous rate of change in a variety of practical contexts

2.4.1.2

use a numerical technique to estimate a limit or an average rate of change

2.4.1.3

examine the behaviour of the difference quotient [𝑓(𝑥+ℎ)−𝑓(𝑥)]/h ℎ as ℎ→0 as an informal introduction to the concept of a limit

2.4.1.4

differentiate simple power functions and polynomial functions from first principles

2.4.1.5

interpret the derivative as the instantaneous rate of change

2.4.1.6

interpret the derivative as the gradient of a tangent line of the graph of 𝑦=𝑓(𝑥)

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