In this problem, we need to plug in the given x values for 
and find a and b.
When we plug in 1, we get:
Simplify:
We got our first statement about the values of the variables. If we find one more we can find those 2 variables.
We have another given root: 4.
Plug it in:
Now we have our second one. We can combine them:
I use elimination method which is easier here.
Multiply the top equation by -1:
Add them up:
Simplify:
Now we have a, we can plug in one of those equations to find b:
So, the answers are
and 
.
When we plug in 1, we get:
Simplify:
We got our first statement about the values of the variables. If we find one more we can find those 2 variables.
We have another given root: 4.
Plug it in:
Now we have our second one. We can combine them:
I use elimination method which is easier here.
Multiply the top equation by -1:
Add them up:
Simplify:
Now we have a, we can plug in one of those equations to find b:
So, the answers are