Question

До какого числа должно измениться значение счетчика i в фрагменте программы, чтобы C стало равным 14? C:=2; for i:=3 to … do C:=C+i;

Answer 1

Ответ:

i должен бежать от 3 до 5

Объяснение:

for i := 3 to 5 do

Answer 2

To find the value of the counter i at which C becomes equal to 14, we need to solve the equation:

C = 2 + 3 + 4 + ... + i

To simplify the sum of consecutive integers from 3 to i, we can use the formula for the sum of an arithmetic series:

Sum = (n/2) * (first term + last term)

In our case, the first term (a) is 3, and the last term (l) is i. We want the sum to be 14, so we can set up the equation:

14 = (i/2) * (3 + i)

Now, let's solve for i:

14 = (i/2) * (3 + i) 14 = (i/2) * (i + 3) 14 = (i^2 + 3i) / 2

Multiply both sides by 2 to eliminate the denominator:

28 = i^2 + 3i

Now, let's rearrange the equation to form a quadratic equation:

i^2 + 3i - 28 = 0

Now, we can factorize the quadratic equation:

(i + 7)(i - 4) = 0

Now, set each factor to zero and solve for i:

1. i + 7 = 0 i = -7

2. i - 4 = 0 i = 4

So, the possible values of i are -7 and 4. However, the counter i cannot have a negative value in the context of a "for" loop, so the value of i should be 4.

Therefore, the value of the counter i should be changed to 4 in the given program to make C equal to 14. The updated code will look like:

cCopy code
C := 2;
for i := 3 to 4 do
    C := C + i;

Executing this code with i starting from 3 and incrementing up to 4 will give us C = 14.