Answer: 
Step-by-step explanation:
Given the quadratic equation
, you need to factor it.
In order to find the form asked of the given equation, you need to factor out the common factor of the terms.
You can observe that the common factor of the terms of the equation is: 
Now, knowing this, you must factor out
. Then you get the following form:

Therefore, the factored fom of the equation
is:

Answer:
78
Step-by-step explanation:
Given that:
First day (a) = 1
1 more pebble every subsequent day than the previous day
Tn = a + (n - 1)d
d = common difference ; difference between pebbles in two successive days = 1
n = nth day
At the end of the 12th day;
Tn = a + (n - 1)d
T(12) = 1 + (12 - 1) 1
T(12) = 1 + 11
T(12) = 12
Appling the sun if arithmetic progression formula : Sum of AP:
n/2 (a + Tn)
n = number of terms
12/2 (1 + 12)
6(13)
= 78