# I need help evaluating this numbers

• 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
• 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)

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

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

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

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

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

To finish the problem you must create a common denominator

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

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

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

Originally Posted by pickslides
$\displaystyle y=\frac{45-90-400}{100}$

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)

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

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