Answer:

Explanation:
We can take out 2 to as this is common in each term:


We can see that the use factors of 21 which are 1, 3, 7 and 21 (all ± values). We can use -7 and the coefficients of the simplified expression to determine if one of the values is zero when -7 is multiplied and added to the coefficients:
-7] 1 7 3 21
Bring down 1
-7] 1 7 3 21
____-7_ 0_-21____
1 0 3 0
We can see that the factor of -7 yields two zeros, but the final answer is zero and therefore we can use 7 factor and the answers it yielded:
We can simplify the expression using 1, 0 and 3.

