7,8(6,3+13,7)=7,8*20=78*2=156
1) - 8•( 3/16х - 5/8y ) = - 3/2x + 5y = - 1,5x + 5y
2) ( -3 )•( - 2/9x - 5/6 ) = 2/3x + 5/2
3) - 1,5x + 5y - ( 2/3x + 5/2 ) = - 1 1/2x + 5y - 2/3x - 2,5 = 5y - 1 3/6x - 4/6x - 2,5 = 5y - 1 7/6x - 2,5 = 5y - 2 1/6x - 2,5
Решение смотри во вложении.
(x-2)(x-4)=(x+3)(x+2)
x*x-x*4-2*x+8=x*x+2*x+3*x+6
x*x-x*x-6*x-5*x=6-8
-11*x=-2
x=2/11
((х^2-10х+25)/(х^2-25))^3:((х-5)/(х+5))^3=1
((х-5)^2 /(х-5)(х+5))^3:((х-5)/(х+5))^3=1
(х-5 / х+5 )^3 : (х-5 /х+5)^3 =1
(х-5 / х+5 )^0 =1
1=1
а^0=1
а^m :a^n =a^m-n у нас
а^3 :а^3=а^3-3 =а^0=1