Question

Показать, что значение: (3x-8)^2+(4x-8)(4x+8)+100x при x=-2 равно -4

Answer 1

Упростим для начало само выражение, получим 
(3x - 8)^2 + (4x + 8)(4x - 8) + 100x = 
= 9x^2 - 48x + 64 + 16x^2 - 64 + 100x = 
= 25x^2 + 52x 

x = - 2
25(-2)^2 + 52(-2) = 100 - 104 =  - 4

Answer 2

To show that the value of the expression (3x-8)^2 + (4x-8)(4x+8) + 100x at x=-2 is equal to -4, we'll simply substitute x=-2 into the expression and perform the calculations step by step.

Given expression: (3x-8)^2 + (4x-8)(4x+8) + 100x

Let's substitute x with -2:

Step 1: Calculate (3x-8)^2 (3(-2) - 8)^2 = (-6 - 8)^2 = (-14)^2 = 196

Step 2: Calculate (4x-8)(4x+8) (4(-2) - 8)(4(-2) + 8) = (-8)(0) = 0

Step 3: Calculate 100x 100(-2) = -200

Now, put all the results together:

(3x-8)^2 + (4x-8)(4x+8) + 100x = 196 + 0 - 200 = -4

Thus, the value of the expression at x=-2 is indeed -4, as required.