# Thread: Can you explain to me how to do this?

1. ## 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??

7x+2y= -28

and

21d*d+85d-26=0

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

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

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:

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

You'll need to factor out here.

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

Thus:

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

OR

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