root

Are you trying to factor it or the square root of it? Also, I assume it is 2x^2-3x-1=0 while ^2 means 2x squared.
meh?
 
one solution

ok I got the other one but what do they mean when they say, one solution of
l12-3xl=9 is x=1. The other solution is x=?

I really don't understand
 
|z| means modulus of z. That is, whatever the sign (+ or -) of the value of z, |z| is the positive equivalent (or zero).

For example,
|3| = 3
|-6| = 6
|6| = 6
|0| = 0

Now if you had |y| = 1 there are two possible values for y.
Firstly, assume y is positive or zero (y >= 0). In this case, regardless of what y is, |y| = y (because |y| just asks for the positive equivalent of y and y is already positive).
You would then have |y| = y = 1. This is your first answer for |y| = 1

But you must also consider the possibility y is negative (y < 0). Since |y| converts y to a postive value, you can say that if y < 0 then |y| = -y (since if y is negative, -y will be positive).
Therefore, |y| = -y = 1, y = -1

Hence, if |y| = 1, then y = 1 or y = -1.

In relation to your question, you need to consider two possibilities:

If 12 - 3x >= 0 (positive)
Then |12 - 3x| = 12 - 3x = 9
3x = 12 - 9 = 3
x = 1

If 12 - 3x < 0 (negative)
Then |12 - 3x| = -(12 - 3x) = 9
-12 + 3x = 9
3x = 21
x = 7

So the other solution is x = 7.

Hope that helps (and sorry for being so long-winded).

crestu
 
l12-3xl=9

That means: 12 - 3x = 9 or 3x - 12 = 9

Solve both.
 
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