The coefficient is 4 because it is placed before x.
You should divide 280 into 3 which would equal 9
Answer:
2520 patterns
Step-by-step explanation:
In 'n' 10! ways, books can be arranged. But, there are also 5! permutation of blue books 'n1', 2! permutation of identical green books 'n2', and 3! permutation identical black books 'n3'.
Therefore, for non identical arrangements:

= 2520
Therefore, the books can be arranged on a shelf in 2520 patterns
The square root of 69 is 8.30.because 8.30*8.30 is 69