There are 15 questions in total, 8 points for one right question, 4 points for one wrong question and 72 points for Xiao Ming. How many questions have you answered correctly? You can't use negative numbers or X to express, the simpler the better

There are 15 questions in total, 8 points for one right question, 4 points for one wrong question and 72 points for Xiao Ming. How many questions have you answered correctly? You can't use negative numbers or X to express, the simpler the better

(15*8-72)/(4+8)=4
That is to say, if you do it all right, you should get (15 * 8) and 120 points. However, if you do a wrong question, you will not get 8 points, but also get 4 points. Therefore, if you do not do a wrong question, it is equivalent to deducting (8 + 4) and 12 points from the full score of 120 points. Therefore, you will definitely deduct (120-72) and 48 points. That is to say, you have done four wrong questions
15-4=11
I got 11 questions right

The mathematics interest group held a test. There were 15 questions in the whole paper. It was stipulated that 8 points would be deducted for each right question and 4 points would be deducted for each wrong question. Xiaoying got 72 points in total, and she did it right______ Question

The wrong questions are: (8 × 15-72) △ 8 + 4, = (120-72) △ 12, = 48 △ 12, = 4 (DAO); he did right: 15-4 = 11 (DAO); a: he did right 11 questions. So the answer is: 11

In a math contest, there are 15 questions, each of which gets 8 points. For each wrong question, 3 points will be deducted. Xiao Ming's score is 65 points. How many questions did he do right?

Full Score 15 * 8 = 120
Each wrong question is 8 + 3 = 11 points less than the right one
The total score is 120-65 = 55
So we made a total of 55 / 11 mistakes
Xiao Ming did 15-5 = 10 questions correctly

log2(2x)*log2(x)=2 x=?

[log2 (2) + log2 (x)] * log2 (x) = 2 / / import formula loga (b * c) = loga (b) + loga (c)
[1+log2(x)]*log2(x)=2
Let log2 (x) = t, then
(1+t)*t=2
t^2+t-2=0
T = 1 or T = - 2
That is log2 (x) = 1, x = 2
Or log2 (x) = - 2, x = 2 ^ (- 2) = 1 / 4

The speed of a car is 1.5 times that of a motorcycle. It takes 4 hours for a car to travel 300 km. How many hours does it take for a motorcycle to complete the journey?

A: it takes 6 hours for the motorcycle to finish the journey

We stipulate: "an equation with an unknown number, an unknown number, and the highest exponent of the unknown number is 2 is called a quadratic equation with one variable, such as
For example: x ^ 2-2x + 1 = 0. It is known that the solution of the univariate quadratic equation AX ^ 2 + BX + C = 0 (a, B, C are known quantities, a is not equal to 0) is as follows:
b²-4ac>0
b²-4ac=0
b²-4ac

1. Because B & # 178; - 4ac
=（-4）²-4×1×（-5）
=36>0
So there are two unequal solutions for the quadratic equation x of one variable to the second power - 4x - 5 = 0
2. According to the meaning of the title, we get (- 2) &# - 4 × 1 (A-2) = 0
The solution is a = 3
So when a is 3, there are two equal solutions to the quadratic equation x of one variable with respect to X to the second power - 2x + (A-2) = 0
3. Because in the equation 1 / 2x to the second power - (a + 2) x + A-1 = 0
b²-4ac
=(a+2)²-4×（1/2）*(a-1)
=a²+2a+6
=(a+1)²+5≥5>0
So quadratic equation of one variable has two unequal solutions

Galaxy Solar System Earth Moon universe

Universe > Galaxy > solar system > Earth > moon

How to solve x minus 15%

x-15%x=68
85%x=68
x=68÷85%
x=80
If you have any new questions, please don't send them in the form of follow-up questions, send them to me for help or send them to the question link address,

I'm learning liquid pressure recently. I'm dizzy``
1. There is pressure in all directions under the water, isn't it? Is it true at any point in the water?
2. An object is also subject to pressure in all directions underwater, right? If the pressure in all directions is equal, then the object is subject to equilibrium force underwater, and the resultant force is 0? Isn't it subject to great pressure?
3. If we find out the pressure of X PA on an object under water, where is the pressure? All directions are common?
4. Conceptually speaking, "there is pressure in all directions inside the liquid" and "outward pressure" is the same as the pressure at each point?
Maybe some of the questions are silly, which makes me understand that I haven't mastered the new learning content,
Thank you. First floor, though```
Second, you say that it is equivalent to no force. What is the pressure of N PA on an object under water? Isn't it necessary for a submarine to have a very thick shell to resist the pressure of water? How can the resultant force be zero?
Hard work, hard work, but I don't understand. Can we talk about it again?

If you are in the water, if you ignore the size of your body and regard your body as a point, no matter what posture you hold, the pressure you receive is the same, but the direction is different. Of course, the premise is that the depth remains unchanged. 2

The teacher wrote a question on the blackboard: solve the inequality x + 2 divided by 2 ≥ 2x-1 divided by 3 + an unknown number, please ask this unknown number

/2≥+3
x+2≥4x-2+6
-3x≥2
x≥-2/3