To check for continuity at the edges of each piece, you need to consider the limit as 
approaches the edges. For example,
has two pieces, 
and 
, both of which are continuous by themselves on the provided intervals. In order for 
to be continuous everywhere, we need to have
By definition of , we have 
, and the limits are
The limits match, so is continuous.
For the others: Each of the individual pieces of 
are continuous functions on their domains, so you just need to check the value of each piece at the edge of each subinterval.
Answer :
Step by Step Explanation :
1. 6x - 30 - 4x = 12x - 15
2. 2x - 30 = 12x - 15
3. -10x - 30 = -15
4. -10x = 15
5. x = -10/15
6. x = -2/3 (simplified)
The last terms must multiply to the last terms (confusing)
example
if ax^3+bx^2+c+d=(ex+f)(gx+h)(jx+k) then
d=fhk
so
70 is last term
we got 2 and 5
2*5*?=70
10*?=70
divide by 10
?=7
the missing number is 7
