How much is 0.5% x minus 1.5 equal to 1 minus 0.2% 0.4x plus 1

How much is 0.5% x minus 1.5 equal to 1 minus 0.2% 0.4x plus 1

x/0.5-1.5=4x/1-0.2
2x-1.5=5x
-3x=1.5
x=-0.5

Proof: the function f (x) = x + 1 / X is a decreasing function in the interval (0,1)

First, we get the derivative
f'(x)=1-1/x^2=(x^2-1)/x^2
So when x ∈ (0,1), then
f'(x)

Why is a number divided by a fraction equal to a number multiplied by the reciprocal of the fraction?
I know the definition is correct, but I want to know the reason and basis

A divided by B = a times 1 divided by B = a times (1 divided by B) = the reciprocal of a times b
It doesn't have to be fractional, as long as it's a non-zero number,

There is a polynomial which only contains the letter X, its degree is 2, and the coefficients of quadratic term and primary term are - 1, and the constant term is 2. Try to write this polynomial
And find out the value of this polynomial when x = - 1 of 2

-x²-x+2
When x = - 1 / 2, the original formula is 9 / 4

There is a box of chocolates. There are 7 chocolates, 7 chocolates, 4 chocolates left, 5 chocolates, 5 chocolates, 3 chocolates left. How many chocolates are there in this box

7(n-1) +4 = 5(n+2) -3
7n-3 = 5n + 7
2n = 10
n = 5
This box of chocolates is at least half full
5 (n + 2) - 3 = 32 grains
or
7 (n + 1) + 4 = 32 grains

The position of the rational number ABC on the number axis is shown in the figure. Simplification: | A-B | - | C-A | - | C + B |
——c——0————b——————a

|a-b|-|c-a|-|c+b|
=a-b-(a-c)-(b+c)
=a-b-a+c-b-c
=2b

[(2 / 3 + 1 / 4) * 3 / 4] divided by 5 / 8

Hello: [(2 / 3 + 1 / 4) * 3 / 4] divided by 5 / 8 = (2 / 3x3 / 4 + 1 / 4x3 / 4) X8 / 5 = (1 / 2 + 3 / 16) X8 / 5 = 1 / 2x8 / 5 + 3 / 16x8 / 5 = 4 / 5 + 3 / 10 = 11 / 10. If you don't understand this question, please follow up. If you are satisfied, please accept it. If you have any other questions, please click

Given that 4x ^ 2 + KX + 49 is a complete square, then the value of K is

4x^2+kx+49
=(2x+7)²
=4x²+28x+49
So k = 28

How to calculate 19.52 - (9.52 + 3.4)

19.52-（9.52+3.4） =19.52-9.52-3.4 =10-3.4 =6.6

If the value of the polynomial 2x & # 178; - ax + 3y-b + BX & # 178; + 2x-6y + 5 has nothing to do with the letter X, try to find the value of a polynomial

Original formula = 2x ^ 2-ax + 3y-b + BX ^ 2 + 2x-6y + 5
=(2+b)x^2-(a-2)x+(3-6)y-b+5
From the meaning of the title, we can get: 2 + B = 0, A-2 = 0
The solution is a = 2, B = - 2
The original formula = - 3Y + 2 + 5
=-3y+7