Х+3=0,5х-2; х-0,5х=-3-2; 0,5х=-5; х=-5:0,5; х=-10.
у=0,5×(-10)-2; у=-7. Ответ: х=-10, у=-7
(с-863)=39765:1205
С-863=33
С=33+863
С=896
(5020+z)=36054*23
5020+z=829242
Z=829242-5020
Z=824222
648. б) b1 = 500, q = 1/5
S(5) = b1*(1 - q^5) / (1 - q) = 500*(1 - 1/3125) / (1 - 1/5) =
= 500*(3124/3125) / (4/5) = 500*3124/3125*5/4 = 624,8
649. а) b1 = 3, b2 = -6, q = b2/b1 = -6/3 = -2
S(6) = 3*((-2)^6 - 1)/(-2-1) = 3*(64 - 1)/(-3) = -63
в) b1 = -32, b2 = -16, q = b2/b1 = (-16)/(-32) = 1/2
S(6) = -32*(1 - (1/2)^6) / (1 - 1/2) = -32*(1 - 1/64) / (1/2) =
= -32*2*63/64 = -63
650. а) c1 = -4, q = 3
S(9) = -4*(3^9 - 1)/(3 - 1) = -4*(19683 - 1)/2 = -2*19682 = -39364
20:8=2,4
5*2,4=12,5
Ответ: 12 рублей, 5 копеек
1) <span>1/8 +1/12=12/96+8/96= 20/96=10/48= 5/24
2) </span><span>3/8 + 5/12= 36/96+40/96=76/96=38/48=19/24
3) 19/24+5/24= 24/24= 1
Ответ: 1</span>