Math problems with unary linear functions and unary linear inequalities

1) A: y=25+

B: y=2) Obviously, the unit price of A is low.

But at the beginning, it is obvious that A is expensive, x=0, A's is 25, and B's is 0, so if you need A, it is worth it.

x>=125

That is, if the customer has played for more than 125 minutes, it is cost-effective to choose A, and it is cost-effective to choose B for less than 125 minutes.

1) Set the call time to x (minutes), and the monthly payment is y (yuan) A 25 + B 0 +

2) Create an equation for these 2 formulas to find out how many minutes they pay the same rate.

25+x=125 (minutes).

1.Conclusion: When A and B just hit 125 minutes, there is no difference between the two charges.

Now let's say you play for 100 minutes and bring in 2 formulas to solve.

A = 25 + yuan) B = 0 + yuan).

2.Conclusion: When the number of minutes is less than 125 minutes, B is cost-effective.

Now let's say you play for 130 minutes and bring in 2 formulas to solve.

A = 25 + yuan) B = 0 + yuan).

3.When the number of minutes is greater than 125 minutes, A is cost-effective.

1) A: y=25+

B: y=2) 25+>=

x<=125, that is, when x=125min, the two services have the same phone charge, when you want to < 125min, 25+>, then service B is cost-effective, if x>125min, service A is cost-effective.

According to the property of inequality 2, when the two sides are in the same potato annihilation, multiply by 3, 3x 9, and according to the property of the unequal spike punch 1, add 5 to both sides at the same time, 3x+5 9+5, that is, 3x+5 14 (the family light answer is not unique).

x>-2, the function value is greater than zero. x=-2, the value of the function is equal to zero. x<-2, the function value is less than zero.

The image of the function y=x+2 is a straight line.

The abscissa of the intersection of the line and the x-axis x=-2 is the solution of the equation x+2=0, the set of the abscissa corresponding to the point where the line is located above the x-axis, the set of solutions corresponding to the equality x+2>0, the set of the abscissa corresponding to the point where the line is located in the part below the x-axis, the set of the abscissa of the inequality x+2<0, welcome to visit my blog

The kinship of "one time" (2) - three ones" is not sincere, do not visit.

1. When x=1 y=3, when x=0 y=2, draw in Cartesian coordinate system, 2 points are connected into a straight line, the function value greater than zero is the part of the line above the x-axis, the function value is equal to 0 is the intersection point with the x-axis, and less than zero is the part below the x-axis.

2. Look at the picture and you will understand.

y=6*150*x+(20-x)*5*260 is simplified to obtain y=26000-400*x

y 24000 is 26000-400*x 24000, so x 5

Therefore, it takes at least 20-5=15 people to produce B parts.

(1) y = 150 times 6 times x x + 260 times (20-x) times 5y = 26000-400x

2) Y is greater than or equal to 24000

26000-400x greater than or equal to 24000

x is less than or equal to 5

Send at least 15 people to make the B part.

（1）y=150*6x+260*5（20-x）=-400x+26000

2）-400x+26000≥24000

X 5 requires at least 15 people to make B parts.

（1）y=150*6x+(20-x)*5*260

2) Let y>=24000, get x<=5, then (20-x)>=15, that is, B has at least 15 people.

Solution: Set the big box with a total of x balls, and the small box with a total of 99-x balls x 12+(99-x) 5 10

Multiply 60 at the same time to get :

5x+12(99-x)＞600

5x+1188-12x＞600

7x＜588x＜84

x=84.

The least common multiple of 12 and 5 is 60

A: 2 large boxes and 15 small boxes.

Set up x large boxes and y small boxes.

12x+5y=99

x+y>10

The solution is x<7, y>3

x=2,y=15

It is not easy to solve it with one yuan at a time, and it can be seen from the meaning of the title that the number of large boxes must be 2, and the number of words in small boxes is only 15.

There are x large boxes and y small boxes.

According to the title, there is: 12x + 5y = 99

And x,y satisfies x + y >10

Then look for x,y that satisfies the conditions.

x=2, y=15

So there are 2 large boxes and 15 small boxes.

1. The image of the primary function y=(2m-4)x+2-n passes.

In the first, second, and third quadrants, when the straight line of the primary function intersects with the y-axis, x=0, y0, that is, 2-n 0, and n 2;And when intersecting with the y-axis, y=0, x cavity search 0, i.e., 2m-4 0, i.e., m2;

2. (1) From the above, it can be seen that the daily profit of the workshop y (yuan) = 5x * 160 + 4 (20-x) * 280, that is, the functional relationship between the daily profit of the workshop y (yuan) and x (people) is y = 5x * 160 + 4 (20-x) * 280 = 22400-320x;

2) If the daily profit of the workshop is not less than 25,000 yuan, then 22400-320x 25,000, the solution is x -2600 320, the equation is not solved, it may be that the problem is wrong, if not less than 20,000 yuan, then x, then 20-x, that is, at least 13 people should be sent to do the parts of Xi Li;

3. From the above, it can be seen that substituting the coordinate values of the two points of ab into the equation y=ax+b, the linear equation of the two points of ab is y=x-3, and substituting the point (m, circular excitation 4) into the equation to obtain m=7;

4. Substituting the coordinate value of the point (0,4) into the linear equation y=(m-4)x+5m-6, and solving m=2, the analytical formula of the straight line is y=-2x+4, when y=6, x=(6-4) (2)=-1.

1)2m-4>0

2-n>0

There are m>2, n "Traces 2

2)y=5*160x+4*280(20-x)=22400-320x(0≤x≤20)

Because the maximum profit is 22,400 yuan for oranges, it is impossible to reach 25,000 yuan. You're right, aren't you? Posture??

3) The equation for the straight line ab is x-y-3=0

i.e. m-4-3=0, m=7

4) 5m-6=4, m=2, and the equation is y=-2x+46=-2x+4

2=-2xx=-1

The solution of the unary primary inequality is the corresponding primary function, and the geometric properties of the image, for example, the solution of kx+b>0 is the primary function, y=kx+b, and the range of x above the x-axis, y=f(x) is the function.

When y=0, f(x)=0 is the equation.

When y≠0 f(x)≠0 is an inequality.

For example, a univariate linear function: y=x+3

Unary Linear Inequality: x+3>0 is y>0 of a unary one-time function, and unary one-time inequalities: x+3<0 are y<0 of a one-dimensional one-time function, and the one-dimensional inequality can be regarded as finding the value of the independent variable when the value of the one-time function y>0 (or y<0).

The primary function y=ax+b represents a straight line in a plane Cartesian coordinate system, that is, every point on the line is on y=ax+b, and the unary primary inequality ax+b is greater or less than 0, indicating a region, above or below the line.

Example: y=2x-1

When x=1, y=1, a(1,1).

When x=0, y=-1 b(0,-1).

A and b lines are images of y=2x-1, and 2x-1 0 represents the area below the line.

Don't let the clouds obscure you, hello!

Solution: -3 x 1

3×2≤2x＜1×2

6≤2x＜2

6-1≤2x-1＜2-1

7≤2x-1＜1

Therefore -7 y 1 choose d