Question #f21a9

1 Answer
Apr 5, 2017

Answer:

#(7a-2)(3a-5)#

Explanation:

re-arrange the expression to have the first term positive:
In this case in descending order of powers of #a#

#21a^2-41a+10#

"Find factors of #21 and 10# whose products ADD to give 41."

Note that 41 is odd, which is the sum of an odd and an even.

The largest combination of #21 and 10# is #210#
A sum of #41# is likely to be made of combinations of #7 and 3# with #5 and 2#

#color(white)(........)7" "2" "rarr3xx2= 6#
#color(white)(........)3" "5" "rarr7xx5= ul35#
#color(white)(.............................................)41#

The signs in the brackets will both be negative:

#(7a-2)(3a-5)#