# Can you explain to me how to do this?

• June 8th 2008, 03:49 AM
sweetcitru
Can you explain to me how to do this?
I know that this is fairly simple,
Are there any specific steps that you have to take?? (Thinking)

7x+2y= -28

and

21d*d+85d-26=0

If you can help me that would be really great.
Thank you
• June 8th 2008, 03:55 AM
janvdl
Quote:

Originally Posted by sweetcitru
I know that this is fairly simple,
Are there any specific steps that you have to take?? (Thinking)

7x+2y= -28

and

21d*d+85d-26=0

If you can help me that would be really great.
Thank you

The first one cannot be solved unless you have another expression. It must be solved by simultaneous equations.

For the second one:

$21d^2 + 85d - 26 = 0$

You'll need to factor out here.

$(3d + 13)(7d - 2) = 0$

Thus:

$3d = -13$
$d = \frac{-13}{3}$

OR

$7d = 2$
$d = \frac{2}{7}$