sat functions

[Brynlee]

I need help with the following question,please.
If the function represents a straight line and it’s known that and , find the value of .


Thanks

[Jack]

The equation of a straight line is of the form

where is the slope and is the y-intercept.

The slope can be found by the following formula:
[tex]a=\frac{y_{2}- y_{1}}{ x_{2}- x_{1}} where are the points which the line passes through.

So, in your case the slope is


Therefore the function can be written as



Finally the function can be written as

So the value of is



Second Method

The "GDC way" using CASIO fx-9860 series is
MENU>STAT>Fill List1 with x-values (2 and -1) and List with the corresponding y-values (3 and 4)>CALC(F2)>REG(F3)>X(F1)> the output is a=-0.3333333, b=3.666666.
Then you can graph the linear function y=-0.3333333x+3.666666
MENU>GRAPH>Y1=-0.3333333x+3.666666>DRAW(F6)>F5>Y-CAL>X=10 and the result is Y=0.333333

[Jack]

Thanks Jack!