U(t1) = U(1) = 1 + 3 = 4 м;
U(t2) = U(2) = 2 + 12 = 14 м;
U= U(2) - (1) = 14 - 4 = 10 м;
[x/(x-y) + 2xy/(x^2-2xy+y^2)]* {2x/(x+y) - 1} =
= [x/(x-y) + 2xy/(x-y)^2] * [{2x -(x+y)} / (x+y)] =
= [ {x(x-y)+2xy} / (x-y)^2] * [(x-y)/(x+y)] =
= [(x^2-xy+2xy) / (x-y)^2 * [(x-y)/(x+y)]
= [(x^2+xy)] / [(x-y)(x+y)]=
= x(x+y) / [(x-y)(x+y)]=
=x / (x-y) = (-2) / (-2+1) = (-2)/(-1) = 2
Давно подобное не решал. Надеюсь, правильно.
а) 1/9(18*1/9-20)= 1/9(2-20)= 1/9*(-18)= -2
б) (19/8+11/12)*48/5= 19/8*48/5+11/12*48/5= 19*8/5+ 11*4/5= 152/5+44/5= 196/5= 39,2
в) 21/(6/10*28/10)= 21/(3/5*14/5)= 21/(42/25)= 21:(42/25)= 21*25/42= 25/2= 12,5
г) 5√(11*2*22)= 5√22²= 5*22= 110
д) √90*30*3= √90*90= √90²= 90
е) (√23+1)²= 23+2√23+1= 24+2√23
ж) (-7)²(0,8*(-7)²-0,3)+45= 49(39,2-0,3)+45= 49*38,9+45= 1951,1