Question

8,5х-3(1,4х-7,2)+2,8(9x-7)-2,если x=-0,2

Answer 1

8,5х-3(1,4х-7,2)+2,8(9x-7)-2=

=8,5х-4,2х+21,6+25,2х-19,6-2=29,5х

x=-0,2

29,5х=29,5*(-0,2)=-5,9

Answer 2

To evaluate the expression for a given value of x, simply substitute the value of x into the expression and perform the calculations step by step. Let's do that:

Given expression: 8.5x - 3(1.4x - 7.2) + 2.8(9x - 7) - 2

Now, we are asked to evaluate the expression when x = -0.2.

Step 1: Substitute x = -0.2 into the expression:

8.5(-0.2) - 3(1.4(-0.2) - 7.2) + 2.8(9(-0.2) - 7) - 2

Step 2: Perform the calculations:

8.5(-0.2) = -1.7 1.4(-0.2) = -0.28 9(-0.2) = -1.8

Now, the expression becomes:

-1.7 - 3(-0.28 - 7.2) + 2.8(-1.8 - 7) - 2

-1.7 - 3(-0.28 - 7.2) = -1.7 + 3(7.48) = -1.7 + 22.44 = 20.74 2.8(-1.8 - 7) = 2.8(-8.8) = -24.64

Now, the expression becomes:

20.74 - 24.64 - 2

Step 3: Complete the calculation:

20.74 - 24.64 - 2 = -5.9

So, when x = -0.2, the value of the expression is -5.9.