A5=-2 a25-48 найдите a1 и d

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Given that A5 = -2 and A25 = -48, we can use the arithmetic progression formula to find a1 and d.

The formula for the nth term of an arithmetic progression is: An = a1 + (n-1)d

Substitute n = 5 into the formula:
A5 = a1 + (5-1)d
-2 = a1 + 4d .............(1)

Substitute n = 25 into the formula:
A25 = a1 + (25-1)d
-48 = a1 + 24d ...........(2)

We have a system of linear equations:
-2 = a1 + 4d
-48 = a1 + 24d

Subtract equation (1) from equation (2):
-48 - (-2) = 24d - 4d
-46 = 20d
d = -46/20
d = -2.3

Now substitute d = -2.3 into equation (1):
-2 = a1 + 4(-2.3)
-2 = a1 - 9.2
a1 = -2 + 9.2
a1 = 7.2

Therefore, a1 = 7.2 and d = -2.3.