<span>-(m+5)-(9-m)-7.5=-m-5-9+m-7,5=-13,4
------------------------------
</span><span>(7+a-в)+(3-a)-(8-в)+9=7+a-b+3-a-8+b=2
----------------------------
</span>-2*(3+a)+2a+4*(в-7)=-6-2a+2a+4b-28=-34+4b
====================================
====================================
1 5/6-(у+2/3)=1 1/2
1 5/6-y-2/3=1 1/2
1 5/6-2/3-1 1/2=y
11/6-4/6-9/6=y
-2/6=y
y=-1/3
5х^2 + 9x + 4 = 0
D = 81 - 4*4*5 = 81 - 80 = 1; √D = 1
x1 = (- 9 + 1) / 10 = - 0,8
x2 = ( - 9 - 1) /10 = - 1
Ответ: х1 = - 0,8;
х2 = - 1
Решение:
Дано:
q=-3
S5=-305
Найти b1 ?
Sn=b1*(1-1^n)/(1-q)
-305=b1*[1-(-3)^5] / [1-(-3)]
-305=b1*[1-(-243)] / (1+3)
-305=b1*(1+243) /4
-305=b1*(244/4)
-305=b1*61
b1=-305 : 61
b1=-5
Ответ: b1=-5