Question

Очень срочно помогите пожалуйста. Докажите тождество: 1) -0,2(4b - 9) + 1,4b = 0,6 + 1,8 2) (5а - 3b) - (4 + 5a - 3b) = -4 3) 5(0,4 - 0,3) + (0,8 - 0,6x) = 1,4x - 0,7 4) 1/9(3y - 27) - 2(1/12y - 1,5) = 1/6y

Answer 1

1) -0.2(4b-9)+1.4b=-0.8b+1.8+1.4b=0.6b+1.8       0.6b+1.8=0.6b+1.8
2) (5a-3b)-(4+5a-3b)=5a-3b-4-5a+3b=4                4=4 
3) 5(0.4-0.3)+(0.8-0.6x)=2-1.5+0.8-0.6x=1.3-0.6x   1.3-0.6x≠1.4x-0.7      
4) 1/9(3y - 27) - 2(1/12y - 1,5)=y/3-3-1/6y+3=y/3-1/6y  y/3-1/6y≠1/6y

Answer 2

1. -0,2(4b - 9) + 1,4b = 0,6 + 1,8

First, we can simplify the left-hand side of the equation by distributing the -0.2:

-0.2(4b - 9) + 1.4b = -0.8b + 1.8 + 1.4b

Simplifying further, we can combine like terms:

-0.8b + 1.4b + 1.8 = 0.6 + 1.8

We can simplify the right-hand side as well:

0.6 + 1.8 = 2.4

So now we have:

0.6b + 1.8 = 2.4

Subtracting 1.8 from both sides gives us:

0.6b = 0.6

Dividing by 0.6 gives us:

b = 1

Therefore, the equation is true for b = 1.

2. (5а - 3b) - (4 + 5a - 3b) = -4

Starting with the left-hand side of the equation, we can simplify the expression inside the parentheses:

(5а - 3b) - (4 + 5a - 3b) = 5а - 3b - 4 - 5а + 3b

Simplifying further, we can combine like terms:

5а - 5а - 3b + 3b - 4 = -4

The left-hand side simplifies to:

-4 = -4

Therefore, the equation is true for all values of a and b.

3. 5(0,4 - 0,3) + (0,8 - 0,6x) = 1,4x - 0,7

Starting with the left-hand side of the equation, we can simplify the terms inside the parentheses:

5(0.4 - 0.3) + 0.8 - 0.6x = 5(0.1) + 0.8 - 0.6x

Simplifying further, we can multiply 5 by 0.1:

0.5 + 0.8 - 0.6x = 1.4x - 0.7

Combining like terms, we get:

1.3 - 0.6x = 1.4x - 0.7

Adding 0.6x to both sides, we get:

1.3 = 2x - 0.7

Adding 0.7 to both sides, we get:

2 = 2x

Dividing both sides by 2, we get:

x = 1

Therefore, the equation is true for x = 1.

4. 1/9(3y - 27) - 2(1/12y - 1,5) = 1/6y

Starting with the left-hand side of the equation, we can simplify the terms inside the parentheses:

1/9(3y - 27) - 2(1/12y - 1.5) = 1/3(y - 3) - 1/6y + 3

Simplifying further, we can find a common denominator for the first two terms on the right-hand side:

1/3(y - 3) - 1/6y + 3 = (2/6)(y - 3) - (1/6)y + 3

Combining like terms, we