Number one is x=9,-9
number two is x=0
number three is x=12,-12
number four is 5i, -5i
<span>f(x<0)=-f(x>0)=-x^2+5x+12
When x>0, x^2-5x-12=12, x=8, y=12
Therefore, f(x)=12 goes through point (8,12).</span>
Answer:
a.
and 
Step-by-step explanation:
Let x be the larger number and y be the smaller number.
We have been given that one number is 4 more than another. We can represent this information in an equation as:

We can manipulate this equation as:


We are also told that the sum of both numbers is 60. We can represent this information in an equation as:

Upon looking at our given choices, we can see that option 'a' is the correct choice.
Some useful relations and identities:



By the first relation, we have

Applying the two latter identities, we get

We can apply the third identity again:

and this is probably as far as you have to go, but by no means is it the only possible solution.