Cambridge International Mathematics

28 Graphics calculator instructions

Casio fx-9860G

To find the general term for thequadratic sequence ¡ 2 , 5 , 16 , 31 , 50 , ....,

we first notice that we have been given 5 members of the sequence. Enter the

numbers 1 to 5 intoList 1, and the members of the sequence intoList 2.

Press F2 (CALC) F3 (REG) F3 (Xˆ2).

The result is a=2, b=1, c=¡ 5 , which means the general term for the

sequence is un=2n^2 +n¡ 5.

To find the general term for thecubic sequence ¡ 3 ,¡ 9 ,¡ 7 , 9 , 45 , we enter

the numbers 1 to 5 intoList 1and the members of the sequence intoList 2.

Press F2 (CALC) F3 (REG) F4 (Xˆ3).

The result is a=1,b=¡ 2 ,c=¡ 7 ,d=5(the calculator may not always

give the result exactly as is the case withcanddin this example). Therefore

the general term for the sequence is un=n^3 ¡ 2 n^2 ¡ 7 n+5.

EXPONENTIAL REGRESSION

When we have data for two variablesxandy, we can use exponential regression to find the exponential

model of the form y=a£bx which best fits the data.

x 2 4 7 9 12

y 7 11 20 26 45

We will examine the exponential relationship betweenxandyfor the data:

Texas Instruments TI-84 Plus

Enter thexvalues intoL1and theyvalues intoL2.

Press STAT I 0: ExpReg, then 2nd 1 (L 1 ) , 2nd 2 (L 2 ) ENTER.

So, the exponential model which best fits the data is y¼ 5 : 13 £ 1 : 20 x.

POWER REGRESSION

When we have data for two variablesxandy, we can use power regression to find the power model of the

form y=a£xb which best fits the data.

x 1 3 4 6

y 3 19 35 62

We will examine the power relationship betweenxandyfor the data:

Texas Instruments TI-84 Plus

Enter thexvalues intoL1and theyvalues intoL2.

Press STAT I , then scroll down to A: PwrReg and press ENTER.

Press 2nd 1 (L 1 ) , 2nd 2 (L 2 ) ENTER.

So, the power model which best fits the data is y¼ 3 : 01 £x^1 :^71.

Casio fx-9860g

Enter thexvalues intoList 1and theyvalues intoList 2.

Press F2 (CALC) F3 (REG) F6 F3 (Pwr).

So, the power model which best fits the data is y¼ 3 : 01 £x^1 :^71.

IGCSE01

cyan magenta yellow black

(^05255075950525507595)
100 100
(^05255075950525507595)
100 100
Y:\HAESE\IGCSE01\IG01_00a\028IGCSE01_00a.CDR Tuesday, 4 November 2008 9:49:34 AM PETER