What is the necessary and sufficient condition for the quadratic equation AX2 + 2x + 1 = 0 to have at least one negative real root? Where "AX2" means x squared times a If we use the idea of complement set to solve the problem, we can find that if we use the idea of complement set to solve the problem,

What is the necessary and sufficient condition for the quadratic equation AX2 + 2x + 1 = 0 to have at least one negative real root? Where "AX2" means x squared times a If we use the idea of complement set to solve the problem, we can find that if we use the idea of complement set to solve the problem,

First, delta > = 0,4-4a > = 0
a

If the equation AX + 1x − 1-1 = 0 about X has no real root, then the value of a is______ ．

Equation to denominator: ax + 1-x + 1 = 0, x = 1 into: a + 1-1 + 1 = 0, solution: a = - 1. So the answer is: - 1

On the equation AX = B of X, when_____ The equation has only one solution; X=_____ ; when______ The equation has innumerable solutions____ The equation has no solution

On the equation AX = B of X, when__ a≠0___ The equation has only one solution; X=__ b/a___ ; when___ A = 0 and B = 0___ The equation has innumerable solutions_ A = 0 and B ≠ 0___ The equation has no solution

1. If a and B are opposite to each other, then | a-5 + B|=___________________________________ .
2. In the following statements, the correct one is ()
A. For any rational number, if a + B = 0, then | a | = | B|
B. For any rational number, if | a | = | B |, then a + B = 0
C. For any rational number, if a is not equal to 0 and B is not equal to 0, then a + B is not equal to 0
D. If the sum of two rational numbers is positive, the two numbers must be positive
3. The rational numbers m and N are opposite to each other, X and y are reciprocal to each other, and the absolute value of Z is equal to 5. Find the value of 2m + 2n + 6xy + Z
1 and 3 should write the method
I don't quite understand

1）5
From the known condition "a and B are opposite numbers", then a + B = 0, (the sum of two opposite numbers is zero), | a-5 + B | = | (a + b) - 5 | = | 0-5 | = | - 5 | = 5
2）A
3) 11 or 1
m. If n is opposite to each other, then M + n = 0;
x. If y is reciprocal to each other, then x = 1;
If the absolute value of Z is equal to 5, then | Z | = 5, that is, z = 5 or Z = - 5;
2m + 2n + 6xy + Z = 2 (M + n) + 6 * 1 / y * y + Z = 0 + 6 * 1 + Z = 6 + Z, so when z = 5, the answer is 11, and when z = - 5, the answer is 1
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There are 100 chickens and 80 ducks. The number of ducks is ()%,

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Ask the first volume of the first day of junior high school mathematics exercise book 1.3.1 rational number addition (2) answer, tomorrow will hand in!
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You can add 20-30 points

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It is known from the sequence that there are 2N-1 terms in the nth term, and the last number of the nth term is 1 + 3 + 5 + +(2n-1) = 1 + 2n − 12 × n = N2, an = (1 + 2 + 3 +...) +n2）-[1+2+3+… +（n-1）2]=（n-1）2+1+（n-1）2+2+… +（n-1）2+（2n-1）=（n-1）2×（2n-1）...

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The formula method of the application problem of the equation of one degree with one variable
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Write by formula

This is a univariate quadratic equation, right? If so, let the solution be x (90 + x) (40 + x) = 90 * 40 / 0.72 (90 + x) (40 + x) = 50003600 + 90x + 40x + X & sup2; = 5000x & sup2; + 130x-1400, because B & sup2; - 4ac = 11300, so x = [- B ± √ (b ^ 2-4ac)] / 2ax1 = - 140, X2 = 10x1 does not conform to the meaning of the problem