Question

2. При каком значении переменной a значение выражения -7(а-4) на 86 больше значения выражения 5(a -8) ? Составить и решить уравнение. РЕШИТЕ ПОЖАЛУЙСТА!! ​

Answer 1

Если перед скобками стоит знак минус, то знаки в скобках меняются на противоположные.

-7(а - 4) = 5(а - 8) + 86

-7а + 28 = 5а - 40 + 86

-7а - 5а = 46 - 28

-12а = 18

а = 18 : (-12)

а = -1,5

Ответ: при а = -1,5.

Проверка:

-7 · (-1,5 - 4) = -7 · (-5,5) = 38,5 - значение первого выражения

5 · (-1,5 - 8) = 5 · (-9,5) = -47,5 - значение второго выражения

38,5 - (-47,5) = 38,5 + 47,5 = 86 - разница (по условию задачи)

Answer 2

Problem Analysis

We are given the expression -7(a-4) and the expression 5(a-8). We need to find the value of variable a for which the value of -7(a-4) is 86 greater than the value of 5(a-8). To solve this problem, we can set up an equation and solve for a.

Equation Setup and Solution

Let's set up the equation: -7(a-4) = 5(a-8) + 86

Now, let's solve the equation step by step:

Step 1: Distribute the -7 and 5 to the terms inside the parentheses: -7a + 28 = 5a - 40 + 86

Step 2: Combine like terms on both sides of the equation: -7a + 28 = 5a + 46

Step 3: Move the variables to one side and the constants to the other side: -7a - 5a = 46 - 28

Step 4: Simplify both sides of the equation: -12a = 18

Step 5: Divide both sides of the equation by -12 to solve for a: a = -18/12

Step 6: Simplify the fraction: a = -3/2

Therefore, the value of variable a that satisfies the given condition is a = -3/2.

Please let me know if you need any further assistance.