Sunday, February 7, 2010

Just check my answer to this true or false question please?

The graph of y = 6(x - 8 )^2 + 1 opens downward


is that true or false?





I think true right?Just check my answer to this true or false question please?
Let's make a value list, around x = 8:





x | y


5 | 6(8-5)^2+1 = 6*9+1 = 55


6 | 6(8-6)^2+1 = 6*4+1 = 25


7 | 6(8-7)^2+1 = 6*1+1 = 7


8 | 6(8-8)^2+1 = 6*0+1 = 1


9 | 6(8-9)^2+1 = 6*1+1 = 7


10 | 6(8-10)^2+1 = 6*4+1 = 25


11 | 6(8-11)^2+1 = 6*9+1 = 55





If you draw this, you see that it ';comes from the sky at the left';, ';bottoms out at x=8 with value 1';, and then ';flies to the skies again';.


So no, it ';opens'; upwards.

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