Question

А2-а5=7.8 а3=-1.8 d-? a1-?​

Answer 1

а5 = а2 + 3d, значит:

а2 - а5 =

= а2 - (а2 + 3d) = 7,8,

а2 - а2 - 3d = 7,8,

-3d = 7,8,

d = -1,6,

а3 = а1 + 2d, значит:

а1 = а3 - 2d = -1,8 - 2 * (-1,6) = -1,8 + 3,2 = 1,4

Answer 2

It seems like you've provided a sequence of equations involving variables and constants. However, the equations aren't entirely clear. It looks like you have some sort of pattern or relationship between the variables. Could you please provide more context or information about what you're trying to solve or describe? This will help me provide a more accurate response.