Question

(y-5)²-y(y+4)-21 при y=1/7​

Answer 1

Ответ: 2

При у= 1/7

(1/7-5)^2-(1/49+4/7)-21 = (-34/7)^2-29/49-21= 1156/49-29/49-21= 23-21= 2

Пошаговое объяснение:

Answer 2

To evaluate the expression (y-5)² - y(y+4) - 21 at y = 1/7, we substitute the value of y into the expression and perform the necessary calculations.

Let's start by substituting y = 1/7 into the expression:

(1/7 - 5)² - (1/7)(1/7 + 4) - 21

Next, simplify each part of the expression:

(1/7 - 35/7)² - (1/7)(29/7) - 21

(-34/7)² - (29/49) - 21

(1156/49) - (29/49) - 21

Now, combine the fractions:

(1156 - 29)/49 - 21

1127/49 - 21

To subtract fractions, we need a common denominator. In this case, the common denominator is 49:

(1127 - 21 * 49)/49

(1127 - 1029)/49

98/49

Finally, simplify the fraction:

2

Therefore, when y = 1/7, the expression (y-5)² - y(y+4) - 21 evaluates to 2.