solving equation, using formula

karl · 2008-05-02 05:40:42

using the formula

X = -b ± √ b² - ac
2a

solve the equation 5x² - 9x + 2 = 0

would be great help if some one could show me a step by step way of working this out.

Thanks karl

karl · 2008-05-02 05:57:32

using the formula

X = -b ± √ b² - ac
______________
2a

solve the equation 5x² - 9x + 2 = 0

would be great help if some one could show me a step by step way of working this out.

Thanks karl

mathsyperson · 2008-05-02 06:44:16

The formula you have is the solution to ax² + bx + c = 0.

In your case, a=5, b=-9, c=2. Put those numbers into the formula to get out your answer.

karl · 2008-05-02 07:20:09

so it would then be writen

x = -9 ± √ -9² - 5 - 2
____________________
2 X 5

so do i do the hole sum adding the -9 to the square routed section to get one answer

then do it all again taking the -9 from the square routed section

to give the two possible answers ??

thanks for the help karl

mathsyperson · 2008-05-02 10:14:53

Kind of, but it's the square rooted bit that you either add or take away. The -9 is always there.

Also, you've got a mistake in your quadratic formula (sorry for not noticing this earlier).
It should be:

Note the 4ac in the square root, instead of just ac.

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