Question

(m-3)(m+3)
(c-7)(c+7)
(4+5a)(5a-4)

Answer 1

^2-это в квадрате
1.m^2+3m-3m-9=0
m^2-9=0
m^2=9
m=+-3
2.с^2+7c-7c-49=0
c^2-49=0
c^2=49
c=+-7
3.20a-16+25a^2-20a=0
-16+25a^2=0
25a^2=16
a^2=25/16
a=5/4