Если решите все даю 75 баллов!ПОЖАЛУЙСТА ПОМОГТЕ

$1) \\ a^{2} - 64 = a^{2} - 8^{2} = (a - 8)(a + 8) \\ 9m^{2} - 25 = (3m)^{2} - 5^{2} = (3m - 5)(3m + 5) \\ x^{2} +14xy+ 49 y^{2} = (x + 7y)^{2} = (x + 7y) (x + 7y) \\ 2) \\ (5x - y)^{2} - (y+5x)^{2}= 25x^{2} - 10xy + y^{2} - y^{2} - 10xy - 25x^{2} = - 20xy \\ 3) \\ 6,8^{2} = (7-0,2)^{2} = 7^{2} - 2*7*0,2 + 0,2^{2} = 49 - 2,8 + 0,04 = \\ = 46,2+ 0,04 = 46,24 \\ 31^{3} = (30 + 1)^{3} = 30^{3}+3*30^{2}*1 +3*30*1^{2} + 1^{3} = \\ =27000 + 2700 + 90 + 1 = 29 791 \\$

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$4) \\ (x -6m)^{2}= x^{2} -12mx + 36m^{2} \\ (5a +2)^{3}= (5a)^{3} + 3*(5a)^{2}*2 + 3*(5a)*2^{2} + 2^{3} = \\ =125a^{3}+30a^{2}+60a + 8 \\ (p^{3}g-3r^{2})(p^{3}g+3r^{2}) =( p^{3}g)^{2} - ( 3r^{2})^{2} = p^{6}g^{2} - 9r^{4} \\ 5) \\ x^{2}-18x + 60 = x^{2}- 2*9*x + 9^{2} - 9^{2} + 60 = \\ = (x^{2}- 2*9*x + 9^{2}) - 9^{2} + 60 = (x- 9)^{2} - 81 + 60 = (x- 9)^{2} -21 \\$