When x = 3, y = 9, what is the functional relationship between Y and X

When x = 3, y = 9, what is the functional relationship between Y and X

y=3x

It is proved by definition that the function f = x △ (x-1) is a decreasing function at (1, + ∞)

It is proved that let x1, X2 be on (1, + ∞) and X1 1, X2 > 1 and X1 0, x2-1 > 0, x2-x1 > 0
That is, (x2-x1) / (x1-1) (x2-1) > 0
So: F (x1) - f (x2) > 0 = > F (x1) > F (x2)
X1f (x2) = > F (x) = x / X-1 is a decreasing function on (1, + ∞)

It is proved by definition that the function f (x) = x * x + 1 is a decreasing function on (negative infinity, 0)

f(x)=x²+1
x1 x2 ∈(-∝,0)
x1

If P = | 1-2x | + | 1-3x | +, P = | 1-2x | +, P = | 1-3x | +, P = | 1-2x | +, P = |, P = |, P = |, P +|If the value of 1-9x | + | 1-10x | is constant, then this value is?

2x+3x+4x+5x+6x+7x=8x+9x+10x
When x belongs to a certain range, 1-2x, 1-3x, ---- 1-7x are all greater than zero, while 1-8x, 1-9x and 1-10x are all less than zero, that is to say
1-7x>=0,1-8x

Under what circumstances is 1 + 1 not equal to 2?

In case of miscalculation

Using dichotomy to find the roots of equation 2x * x * x-4x * x + 3x-6 = 0 between (- 10,10)

This is relatively easy to do as long as you know what dichotomy is. Here is the program I wrote for reference only (I passed the test in Visual C + + 6.0, and I'm not sure about other compiling systems)
#include
#include
void main()
{
float x0,x1,x2,f0,f1,f2;
do
{
printf("please enter x1 & x2:\n");
scanf("%f,%f",&x1,&x2);
f1=((2*x1-4)*x1+3)*x1-6;
f2=((2*x2-4)*x2+3)*x2-6;
}
while ((f1*f2)>0);
do
{
x0=(x1+x2)/2;
f0=((2*x0-4)*x0+3)*x0-6;
if ((f0*f1)=1e-5);
printf("the root of equation is :%f\n",x0);
}

How many times 11 / 4 equals 0.9 plus how many equals several divided by 5 / 7 equals 1.2;

(4 / 11) multiplied by 11 / 4 = 0.9 + (0.1) = (5 / 7) divided by 5 / 7 = 1.2 × (5 / 6)

LIM (x ^ 2 + 1 - x ^ 2 + x) when x approaches negative infinity

Simple calculation: 1 / 2 * 1 / 3 + 1 / 3 * 1 / 4 + 1 / 4 * 1 / 5 + 1 / 5 * 1 / 6 + 1 / 6 * 1 / 7=

You know, 1 / 2 * 1 / 3 = 1 / 2 - 1 / 3 is easy

A factorization and application problem
1.2x^2-35x-150
2. An average of 20 pieces of clothing are sold every day, with a profit of 40 yuan per piece. In order to meet June 1st, the mall decided to reduce the price. If the price of each piece is reduced by 4 yuan, then 8 pieces can be sold on average. If the average price of each piece is 1200 yuan per day, how much yuan should each piece of clothing be reduced? (use the quadratic equation of one yuan) thank you!

1、2x^2-35x-150 =(x+3)(2x-50)
2. If you reduce the price by 4x yuan per piece, you can sell an additional 8x pieces
（40-4x）*（20+8x）＝1200
4X = 20 or 4x = 10