Answer:
Explanation:
Note the x^2 term, 21 can be divided up into 1,3,7,21
and the constant term, 14 is divisible by 1,2,7
Also, note that -55 = -7*7 - 2*3
Break up 21x^2 into 7x*3x and -55x into -49x - 6x,
21x^2 - 55x + 14
= ((7x*3x) - 49x) - 6x + 14
= 7x*(3x - 7) - 2*(3x -7)
= (7x - 2)*(3x - 7)