Factorization: (A & sup2; + a) (A & sup2; + A-3) - 4 given x + y = 12, xy = 31, finding the fourth power of X + y, 3m-n = 5, Mn = - 2, finding 9m & S

Factorization: (A & sup2; + a) (A & sup2; + A-3) - 4 given x + y = 12, xy = 31, finding the fourth power of X + y, 3m-n = 5, Mn = - 2, finding 9m & S

1. (a ^ 2 + a) (a ^ 2 + A-3) - 4 = (a ^ 2 + a) ^ 2-3 (a ^ 2 + a) - 4 = (a ^ 2 + A-4) (a ^ 2 + A + 1) 2. X + y = 12 xy = 31 x ^ 2 + y ^ 2 = (x + y) ^ 2-2xy = 12 ^ 2-2 * 31 = 82x ^ 4 + y ^ 4 = (x ^ 2 + y ^ 2) ^ 2-2x ^ 2Y ^ 2 = 82 ^ 2-2 * 31 ^ 2 = 48023

If Mn = 2cm, the length of AB is ()
A. 60cmB. 70cmC. 75cmD. 80cm

As shown in the figure, assuming AB = a, then am = 25A, an = 37a, ∵ Mn = 37a-25a = 2, ∵ a = 70

Is 2x Λ - 1 / 3 × 2x Λ - 2 / 3 equal to 4x Λ - 1?

It should be equal to (2x) - 1, because multiplication by the power of the same base number, the base number does not change, and the sum of the exponents of the same base number, 2x is the base number, so do not think that 2x will change to 4x. Be careful to calculate the amount

A is the smallest positive integer, B is the largest negative integer, C is the number with the smallest distance from the origin on the number axis, find the value of a + 2B + C, a is the smallest positive integer, B is the largest negative integer, C is the number with the smallest distance from the origin on the number axis, find the value of a + 2B + C

According to the meaning of the title, a = 1, B = - 1, C = 0
So a + 2B + C = - 1

If (2x-1) quintic = a5x quintic + a4x quartic + a3x & sup3; + a2x & sup2; + A0, then A2 + A4 =?

(2x-1)^5=a5x^5+a4x^4+a3x^3+a2x^2+a1x+a0
When x = 0 (- 1) ^ 5 = - 1 = A0 ①
When x = 1, 1 = A5 + A4 + a3 + A2 + A1 + A0, ②
When x = - 1 (- 3) ^ 5 = - 243 = - A5 + a4-a3 + a2-a1 + A0 ③
② 2 (A4 + A2 + A0) = - 242
That is, 2 (A4 + A2-1) = - 242
The solution is A4 + A2 = - 120
X ^ 2 is the square of X, x ^ 5 is the fifth power of X!

Each phase and zero line of three-phase electricity is 220 V, that is to say, the three lines are the same. Then why is the voltage between two phases 380 V
The single-phase power line divided into three routes is not three-phase power. If not, why? If the expert answers "line voltage", what is the line voltage? I know the voltage between phases. What's the difference between the voltage between each phase of three-phase power and that of a live line divided into three routes

We usually see four low-voltage wires, that is, a, B, C three-phase plus a zero line. A, B, C three-phase are three different live lines. There are still differences between the zero line and the live line. If you really can't distinguish them, you'd better ask the electrician nearby. The voltage between any two live lines is called the line voltage (380V), while one live line and the zero line

Gao Wanjin
Do not change the value of the fraction so that the numerator and denominator of the following fractions do not contain the - sign
-5y
Here's a list. I hope Gao can explain in detail how to do this type of problem, and others want to do it by themselves
-x^2

Both the numerator and denominator of the fraction have negative signs
Negative is positive, so this fraction is greater than 0
When the numerator and denominator are positive and negative
Put the minus sign before time sharing
That is, to align with the fractional line
...

Resistance of induction cooker
The resistance of 22 ohm in the induction cooker is broken when it is replaced. What is the fault?
Pentium induction cooker resistance color ring is red black gold four ring resistance, I don't understand, I don't understand

The 22 ohm resistance is the current limiting resistance of the power supply, and the power supply chip must be burnt out and short circuited. Therefore, we should not only replace the current limiting resistance, but first measure whether the two ends of the filter capacitor are short circuited, and if so, replace the power supply chip

Let's talk about the following fractions
1/x+2 , 4x/x^2-4, 2/2-x

(x-2)/(x^2-4),
4x/(x^2-4),
-2(x+2)/(x^2-4)

How to calculate the maximum load of 6 square copper wire in four connected phase wires

The current carrying capacity of 6 square copper is 6 * 8 = 48 A and 50 a
Three phase voltage is 380, power is 380 * 1.732 * 50 = 33kw