Ask a junior high school math problem!! Urgent!!!!!

A swimming pool every year in June and August ** summer membership card, each membership card 80 yuan, only for personal use, voucher purchase admission ticket 1 yuan each, no voucher purchase admission ticket 3 yuan per ticket:

Under what circumstances do I pay the same amount for a membership card as for not buying a membership card?

Under what circumstances is it more cost-effective to buy a membership card than not to buy a membership card?

Under what circumstances is it more cost-effective to not have a membership card than to buy a membership card?

Note: The problem solving process is complete, step-by-step, and those who can be solved by equations are solved by equations.

80+x=3x

80=2xx=40

x=40, pay the same amount of money for buying a membership card as not buying a membership card.

X>40 is more cost-effective to buy a membership card than not to buy a membership card.

X<40 is not enough to have a membership card, and it is more cost-effective to buy a membership card.

Set 6 8 months to purchase admission tickets x times.

1.When 80+x=3x gets x=40, you will pay the same amount of money for a membership card than for no membership card.

2.At x>40, it is more cost-effective to buy a membership card than not to buy a membership card.

3.At x<40, it is not more cost-effective to purchase a membership card than not to purchase a membership card.

Is there a lack of conditions Otherwise, it's too easy to mention You see, three people buy membership cards Buying three chapter admission tickets is not equal to eighty-one people buying admission tickets without vouchers 1 Answer: 3 * 80 + 3 * 1 = 243 (yuan) = 81 * 3 = 243 (yuan) 2 Answer: The same is true according to the above mentions.

When more than 3 people who purchased a membership card When more than 81 people do not purchase a membership card.

3 Answer: Look at it yourself.

I'm sure you will.

The isosceles right triangle abc has a right angle side length of 10, and the point c represents a circle, and if it rotates 180 degrees, it means that the area of the semicircle is the diameter of the hypotenuse of the isosceles right triangle, and now it is 90 degrees, which is half the area of the semicircle.

75 2 -50 The black part is the area swept Half circle minus two small triangles minus the fan.

Dear, it's okay to send screenshots, it's hard to kiss.

4. Probability: Probability is a measure of the probability of a random event occurring, generally as a real number between 0 and 1. It is often said that the probability of occurrence is often discussed, and the junior high probability problem is mainly such as possible events and independent events.

For example, now a simple analysis, what is the probability that two coin tosses in a row will appear to be heads twice? First of all, if a coin is tossed, the heads and tails may be equal 1 2; And the next coin toss is independent of the previous one. The answer is:

1/4。Students often get stuck in another text problem, what is the probability of heads when a coin is tossed twice in a row? The answer is:

6. Circle: The standard equation for a circle (x a) 2 + (y b) 2 = r2. Knowing that dots and half-valents are also known, it is more straightforward to list the functional expressions of circles using standard equations.

The relationship between circles and straight lines. The circle x2+y2+dx+ey+f=0 (the equation satisfies the condition of the circle: d2+e2-4f>0 can be proved by itself) and the straight line ax+by+c=0, the solution is to convert the circle into a one-dimensional quadratic equation to solve.

i.e. eliminate x or eliminate yThen, according to the deformed one-dimensional quadratic equation, the relationship between the circle and the straight line ( >0, the circle intersects with the straight line; =0, the circle is tangent to the straight line; <0, the circle is separated from the straight line).

Because it is an isosceles right triangle, the two sides are equal in length. Because it is rotated 90 degrees, the swept area is equal to the area of the original triangle, and the Pythagorean theorem is used to calculate the root number of the triangle with the square of ten plus ten squared.

Solution: When the triangle is rotated 90 degrees counterclockwise with C as the center, the area swept by the hypotenuse AB should be centered on C, and the circle should be drawn with any corner edge as the radius, and 1 4 of the circle area is the area.

s=πr^2*1/4

The figure is drawn in a semicircle with a radius of 10, and the area of the semicircle is 50 pai (sorry pai does not).

Subtracting the area of the original triangle 2 by 100 is the result.

1..E and F are the midpoints of OD and OA, so EF parallel is equal to half of AD (triangular median line) Because it is an isosceles trapezoid, AD=BC So EF=GB=CG (G is the midpoint of BC) can be easily known: CEG is similar to BFG

ced is similar to afb fob is similar to eoc ceg is similar to bfg) similar derivation process, you just have to look at their perspective as i wrote) cg=bg so eg=fg

2.From the previous evidence of 120° and 1, it is known that OAB is behind an equilateral triangle, which can be simply deduced.

Large arc plus small arc, 1 4 parks.

Crossing the point T to do TF perpendicular to AB

Because at is the bisector of angle a, ct=tf

Angle adh = angle tdc angle had = angle cad so angle cdt = angle ctd so cd=ct

And because de is parallel to hb, the angle b = the angle e

So the triangle TFB is equal to the triangle cde

So CE=TE and because CE=CT+TE+TB=TE+BE, i.e., CT=BE

There are some omissions in the middle, and you will figure it out by reasoning slowly.

What the hell! How can d, e, and de be parallel to ab in a straight line at ? There are intersection A! Is the topic wrong?

It seems to be a bit of a problem to draw it.。。。

Take advantage of inequalities.

3(a 2+b 2+c 2)>=a+b+c) 2a,b,c>0 equal sign is established only when a=b=c>0)a+b+b+c=3 2a+b+c) 2=9 2, so.

3(a 2+b 2+c 2)=(a+b+c) 2, so a=b=c, it is an isozen reed-edge triangle.

Hope you're satisfied.

70% * 50x for the first donation

Multi(5000-x)*80%*35-70%*50x5000-x)*80%*35+70%*50x=150500 to get x=1500. So. A sells 1,500 pieces. B sells 3,500 pieces.

Is the "home" in the first row a "type A"? Or whatever.