Question

2+4 + ... +2x = 90.​

Answer 1

Ответ:

вот так или у меня ощибка

Пошаговое объяснение:

2+4+82+2=90

Answer 2

To find the value of x in the equation:

2 + 4 + ... + 2x = 90

We need to find the sum of the arithmetic series on the left side of the equation. The sum of an arithmetic series can be calculated using the formula:

S = (n/2)(a + l)

where: S is the sum of the series, n is the number of terms in the series, a is the first term of the series, and l is the last term of the series.

In this case, the first term (a) is 2, and the common difference (d) between consecutive terms is 2. We want to find the value of x, which represents the number of terms.

To find the last term (l), we can use the formula for the nth term of an arithmetic sequence:

l = a + (n - 1)d

In this case, we want the sum to equal 90, so we have:

90 = (x/2)(2 + l)

We can substitute the expression for l in terms of x:

90 = (x/2)(2 + (2x - 2))

Simplifying:

90 = (x/2)(2x)

Dividing both sides by 2:

45 = x^2

Taking the square root of both sides:

x = ±√45

Since x represents the number of terms, it cannot be negative. Therefore, we take the positive square root:

x = √45 ≈ 6.71

So, approximately, x is equal to 6.71.