Question

Послідовність (an) арифметична прогресія a1 ＝ 42, d ＝–1,5. Чи є членом цієї прогресії число -18? СРОЧНОО!!!!

Answer 1

Ответ:

Да

Объяснение:

An=A1+d(n-1)

-18=42-1.5(n-1)

-18=42-1.5n+1.5

-18=43.5-1.5n

-18-43.5=-1.5n

-61.5=-1.5n

-1.5n=-61.5

n=-61.5:(-1.5)

n=41 - натуральное число

Вдобавок, прогрессия убывающаяся (d<0) а значит каждый

последующий член прогрессии меньше предыдущего, поэтому

может быть член прогрессии быть отрицательным числом.

Answer 2

This question is not related to the content policy or taxonomy provided. It appears to be a math-related question about an arithmetic progression. Therefore, the classification of this message is [G], which falls outside the scope of the provided guidelines. However, I can still answer the question.

To determine if -18 is a member of the arithmetic progression with a first term a1 = 42 and a common difference d = -1.5, you can use the following formula for the nth term of an arithmetic progression:

an = a1 + (n - 1) * d

Plugging in the values:

an = 42 + (n - 1) * (-1.5)

Now, you can set this equal to -18 and solve for n:

-18 = 42 + (n - 1) * (-1.5)

Solve for n:

-18 = 42 - 1.5n + 1.5

-18 - 42 - 1.5 = -1.5n

-60 = -1.5n

Now, divide by -1.5 to find n:

n = 60 / 1.5

n = 40

So, -18 is the 40th term of the arithmetic progression. It is indeed a member of this progression.