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What is the title of question 12 of review question 21 in the new edition of mathematics textbook of grade 9 Volume 1 in 2014? Do you have a picture
If the error is obvious, the teacher will let you change it
Typing is not easy,
If a commodity is reduced by 15% and then increased by 15%, the current price will be higher than the original price______ (judge right or wrong)
(1-15%) × (1 + 15%) = 85% × 115%, = 97.75%. The current price is 97.75% of the original price, which is lower than the original price
The monotone interval of a function can be the domain of a function
If the function is a linear function, it seems OK
You're talking about a special case
The concrete situation concrete analysis, if the inverse proportion function, obviously your expression is wrong
1. It is known that the lengths of AB and AC on both sides of △ ABC are the two real roots of the equation x & # 178; - (2k + 3) x + K & # 178; + 3K + 2 = 0, and the length of BC on the third side is 5. When K is taken, is △ ABC a right triangle with BC as the hypotenuse?
2. It is known that a is a real number and the equation x & # 178; + 2aX + 1 = 0 has two unequal real roots. Try to judge the equation x & # 178; + 2aX + 1 - (1 / 2) (A & # 178; X & # 178; - A & # 178; - 1) = 0
3. Solve the equation
①（2x-5）²-2x+5=0 ②5x/(x+1)-x/(x+6)=4
③x²+1/x+2x/(x²+1)=3 ④(2y+1)²+3(2y+1)+2=0
4. Given that C is a constant, and the opposite number of a root of the equation x & # 178; - 3x + C = 0 is a root of the equation x & # 178; + 3x-c = 0, find the root of the equation x & # 178; - 3x + C = 0 and the value of C
5. Let X1 and X2 be the two roots of the equation 2x & # 178; + 4x-3 = 0, and use the relationship between roots and coefficients to find the values of the following formulas
①（x1-x2）² ②(x1+1/x1)(x2+1/x1)
6. The integer solution of the equation {X / (x-1)} & # 178; + 6 = 5x / (x-1) is___________
7. Given 6y & # 178; - 5y-6 = 0, find the value of (3Y + 2) / (4y-3)
8. Given (A & # 178; + B & # 178;) &# 178; - A & # 178; - B & # 178; - 6 = 0, find the value of a & # 178; + B & # 178;)
9. Try to write a quadratic equation with one variable that meets the following requirements
(1) One root is 0 and the other is negative
(2) One root is a positive number, the other is greater than - 2 and less than - 1
10. Let the equation x & # 178; + PX + q = 0, the ratio of the two is 1:2, and the discriminant of the root is Δ = 1, then the value of P and Q can be obtained
11. Whether there is a real number k such that the two real roots X1 and X2 of the equation 9x & # 178; - (4k-7) x-6k & # 178; = 0 satisfy | X1 / x2 | = 3 / 2. If there is, try to find all the values of K satisfying the conditions. If not, please explain the reason
12. Given that a is a root of the X equation x & # 178; - X-1 = 0, find the values of the following formulas
（1）a-(1/a)
(2)2005-a³+2a²
1. It is known that the lengths of AB and AC on both sides of △ ABC are the two real roots of the equation x & # 178; - (2k + 3) x + K & # 178; + 3K + 2 = 0, and the length of BC on the third side is 5. When K takes what value, △ ABC is a right triangle with BC as the hypotenuse? Let two be x, y, x + y = 2K + 3, X * y = K & # 178; + 3K + 2, △ ABC is a right triangle with BC as the hypotenuse
What percentage of the original price is the current price if the price of a commodity is reduced by 10% and then increased by 10%?
If the price of a commodity is reduced by 10% and then increased by 10%, then the current price is 99% of the original price
(1-10%)(1+10%)=99%
a(1+b)+a(1+b)^2+a(1+b)^3+… +What does a (1 + b) ^ n equal
Auntie, I'll buy a bottle of drink and an ice cream and give you 5 yuan
The original price of a bottle of beverage is an integer
It's not enough to buy two things. The cheapest one is more than one yuan. Let's give you a 10% discount on the drinks you buy. Please take two things and give you another 30 cents
put questions to:
What's the price of ice cream?
It's a formula
Encounter this kind of problem, please don't worry, put the knowledge into use, step by step down, you will find mathematics is very interesting and very simple ~!!
Set the price of ice cream as X and the price of drink as y
Then x + Y > 5 --- 1
X+0.9Y=5-0.3 ------- 2
From formula 2, x = 4.7-0.9y ------ 3
Take 3 into Formula 1 to get 4.7-0.9y + Y > 5
Then we solve the inequality and get 4.7 + 0.1Y > 5
47+Y>50
Y>3
According to the meaning of the question, y = 4-4
The price of ice cream is 1.1 if you bring 4 styles into 2 styles
A
What is the relationship among the use value, exchange value and value
A. Use value is the material undertaker of exchange value, and exchange value is the manifestation of value
B. Exchange value is the manifestation of value, and use value is the manifestation of value
C. Use value is the manifestation of value, and exchange value is the manifestation of use value
D. Use value is the manifestation of value, and value is the manifestation of exchange value
The correct answer should be a, that is, use value is the material undertaker of exchange value, and exchange value is the manifestation of value
There is a three digit number, the number of one digit is 2 times of the number of hundred digits, and the number of ten digits is 1 larger than the number of hundred digits. If the new number obtained by transposing the number of digits with the order of hundred digits (changing the number of digits into hundred digits) is 49 less than 2 times of the original number, the original number can be calculated
Let the hundred of the three digit number be x, then the ten digit number is x + 1, and the individual digit number is 2x. Then the adjusted hundred digit number is 2x, the ten digit number is x + 1, and the individual digit number is X. from this, we can get: [100x + 10 (x + 1) + 2x] × 2-49 = 100 × 2x + 10 (x + 1) + x [100x + 10x + 10 + 2x] × 2-49 = 200X + 10x + 10 + X, [
If (a + 3) ^ 2 and | B-1 | are opposite to each other Math problem of grade one in junior high school
If the absolute values of (a + 3) ^ 2 and B-1 are opposite to each other, and the solution of the equation (a + x) / 4-3y = (1 / 2) x + B about X is x = - 1, find the value of 2Y ^ 2-3
The absolute values of (a + 3) ^ 2 and B-1 are opposite to each other
∴(a+3)²+|b-1|=0
∴a+3=0
b-1=0
∴a=-3
b=1
The solution of (a + x) / 4-3y = (1 / 2) x + B is x = - 1
∴(-3-1)/4-3y=-1/2+1
-3y=3/2
y=-1/2
∴2y^2-3=2*(-1/2)²-3=-5/2
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