I know the answer to this is -23, but I do not know the correct working-out to it.So please show working-out. All help is appreciated.

If a=3, b=-2 and c=-5, then the value of 6a+3a-5bsquared-abc=

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- Sep 25th 2007, 12:55 AMMr RayonIncredibly Easy Math Problem
I know the answer to this is -23, but I do not know the correct working-out to it.So please show working-out. All help is appreciated.

If a=3, b=-2 and c=-5, then the value of 6a+3a-5bsquared-abc= - Sep 25th 2007, 01:19 AMjanvdl
$\displaystyle a = 3$

$\displaystyle b = -2$

$\displaystyle c = -5$

$\displaystyle 6a + 3a - 5b^2 - abc$

$\displaystyle = 9a - 5b^2 - abc$

$\displaystyle = 9(3) - 5(-2)^2 - (3)(-2)(-5)$

$\displaystyle = 9(3) - 5(4) - (3)(-2)(-5)$

$\displaystyle = 27 - 20 - 30$

$\displaystyle = 7 - 30$

$\displaystyle = -23$