1+3а=1+3*(-2,5)=1-7,5=-6,5
3(1 - sin²2x) + 7sin2x -3=0
3 - 3sin²2x + 7sin2x - 3=0
3 sin²2x - 7sin2x=0
sin2x(3sin2x - 7) = 0
sin2x=0
и 3sin2x -7 = 0
sin 2x = 7/3 >1 -не является
sin 2x =0
2x= π+ πn
x= π/2 + πn/2
An = a1 + (n-1)d
Система:
a2 + a8 = 10
a3 + a14 = 3
(a1 + d) + (a1 + 7d) = 10
(a1 + 2d) + (a1 + 13d) = 3
2a1 + 8d = 10
2a1 + 15d = 3
2a1 = 10 - 8d
10 - 8d + 15d = 3
7d = 3 - 10
7d = -7
d = -1
a1 = 10 - 8*(-1) = 10 + 8 = 18
a5 = a1 + 4*d = 18 + 4*(-1) = 18 - 4 = 14
17c
-7.5xy
-36c
15ax
26.6c
-2.4by
60a
0.25pq
12b
-7x
-13a
4.6y
-4.4x
некорректная задача
-2.8x
7\12a
-2\7b