Are you sure it's minus 49?
If so, then:
9a2 +42a -49
={(3a)2 + 2·3a·7 + 72} -2·72
=(3a -7)2 - (7·sqrt(2))2 (2nd binomial formula)
={(3a -7) + (7·sqrt(2))} · {(3a -7) - (7·sqrt(2))} (3rd binomial formula)
=(3a +2,89949) · (3a -16,89949).
Otherwise if it's plus 49 then simpler:
9a2 +42a +49
={(3a)2 + 2·3a·7 + 72}
=(3a -7)2.
a2+9a+20 = (a+4)(a+5) when factored
It is 3a(a+3) when factored
9a squared = 81a^2
3a squared plus nine = 19a. 3a to the second power = 9a plus 9 = 19a.
9a- a number is squared when it is multiplied by itself, so 3a x 3a = 9a.
4a2 - 9a + 5 = 4a2 - 4a -5a + 5 = 4a(a - 1) - 5(a - 1) = (4a - 5)(a - 1)
2a+5a+9a = 16a
(9a + 2)(9a + 2)
12a + 6b + 9a + 14b =(12a + 9a) + (6b + 14b) =21a + 20b
9a + 7b *remember to look and understand the letters!*
There is nothing you can do to 9a + 5 without knowing the value of a.
9a+21 3(3a+7)