Cambridge International Mathematics

Graphics calculator instructions 27

Press GRAPH to view the line of best fit.

Casio fx-9860G

Enter thexvalues intoList 1and theyvalues intoList 2using the instructions

given on page 19.

To produce a scatter diagram for the data, press F1 (GRPH) F6 (SET), and

set upStatGraph 1as shown. Press EXIT F1 (GPH 1) to draw the scatter

diagram.

To find the line of best fit, press F1 (CALC) F2 (X).

We can see that the line of best fit is given as y¼ 2 : 54 x+2: 71 , and we

can view therandr^2 values.

Press F6 (DRAW) to view the line of best fit.

QUADRATIC AND CUBIC REGRESSION

You can use quadratic or cubic regression to find the formula for the general term of a quadratic or cubic

sequence.

Texas Instruments TI-84 Plus

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. We therefore

enter the numbers 1 to 5 intoL1, and the members of the sequence intoL2.

Press STAT I 5: QuadReg, then 2nd 1 (L 1 ) , 2nd 2 (L 2 ) ENTER.

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 intoL1and the members of the sequence intoL2.

Press STAT I 6: CubicReg, then2nd 1 (L 1 ) , 2nd 2 (L 2 ) ENTER.

The result is a=1, b=¡ 2 , c=¡ 7 , d=5, which means the general

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

IGCSE01

cyan magenta yellow black

(^05255075950525507595)
100 100
(^05255075950525507595)
100 100
Y:\HAESE\IGCSE01\IG01_00a\027IGCSE01_00a.CDR Tuesday, 4 November 2008 9:53:14 AM PETER