I need help evaluating this numbers

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Nov 12th 2009, 11:30 AM
Cyberman86

I need help evaluating this numbers

x=3/10

evaluate
y=5x^2-3x+4
y=5(3/10)^2 -3(3/10)-1 (How do you evaluate this part, step by step)

y=71/20 (This is the answer)
Nov 12th 2009, 11:49 AM
pickslides

Quote:

Originally Posted by Cyberman86

x=3/10

evaluate
y=5x^2-3x+4
y=5(3/10)^2 -3(3/10)-1 (How do you evaluate this part, step by step)

y=71/20 (This is the answer)

Cyberman, please consider the following.

$y=5\left(\frac{3}{10}\right)^2 -3\left(\frac{3}{10}\right)+4$

$y=5\left(\frac{3^2}{10^2}\right) -3\left(\frac{3}{10}\right)+4$

$y=5\left(\frac{9}{100}\right) -3\left(\frac{3}{10}\right)+4$

$y=\frac{5\times 9}{100} -\frac{3\times 3}{10}+4$

$y=\frac{45}{100} -\frac{9}{10}+4$

To finish the problem you must create a common denominator

$y=\frac{45}{100} -\frac{90}{100}-\frac{400}{100}$

$y=\frac{45-90-400}{100}$

Now finish and simplfy.
Nov 12th 2009, 08:26 PM
Wilmer

Quote:

Originally Posted by pickslides

$y=\frac{45-90-400}{100}$

Last term should be + 400/100
Nov 15th 2009, 11:41 AM
pickslides

Quote:

Originally Posted by Wilmer

Last term should be + 400/100

Thanks Wilmer

I did notice that it could be the case but after reviewing this

Quote:

Originally Posted by Cyberman86

x=3/10

evaluate
y=5x^2-3x+4
y=5(3/10)^2 -3(3/10)-1 (How do you evaluate this part, step by step)

y=71/20 (This is the answer)

I was not sure which sign it could be? How can a +4 become a -1?
Posters should be more careful if they are serious about their education.
Nov 15th 2009, 08:30 PM
Wilmer

Quote:

Originally Posted by pickslides

$y=\frac{45}{100} -\frac{9}{10}+4$
To finish the problem you must create a common denominator
$y=\frac{45}{100} -\frac{90}{100}-\frac{400}{100}$

I only looked at these 2 lines...hence noticed the switch from + to -
Nov 16th 2009, 11:37 AM
pickslides

I think the poster should re-supply the question. (Thinking)
Nov 16th 2009, 12:37 PM
e^(i*pi)

Quote:

Originally Posted by pickslides

Thanks Wilmer

I did notice that it could be the case but after reviewing this

I was not sure which sign it could be? How can a +4 become a -1?
Posters should be more careful if they are serious about their education.

I would say + because 45-90 < 0 and so for the answer to be > 0 it would need to be +400