If the equation x ^ 2 + 2x-c = 0 has an imaginary root of module 2, then the value of real number C is

If the equation x ^ 2 + 2x-c = 0 has an imaginary root of module 2, then the value of real number C is

x=-1±√(1+c)
If it is an imaginary root, then 1 + C

If the equation x ^ 2 + 2x-c = 0 has an imaginary root of module 2, then the value of real number C is?

x=-1±√(1+c)
If it is an imaginary root, then 1 + C

Given the mass and volume of an object, how to calculate its density

Density = mass / volume

Given that the average number of a group of data x1, X2, X3, X4 is 5 and the variance is 2, find the average number and variance of another group of data 3x1-2, 3x2-2, 3x3-2, 3x4-2, 3x5-2

The average is 3 × 5-2 = 13
The variance is 2 × (3 ＾ 2) = 18
If you find it difficult to understand, you can use (3,4,5,6,7) to find the rules
The mean of 3,4,5,6,7 is 5 and the variance is 2

The straight line where a chord of the parabola lies is y = 2x + 5 and the abscissa-3 of the midpoint of the chord is used to find the parabola
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Let the equation of parabola be
y*y=-2pX （p>0）
or
X*X=2qy （q>0）
By simplifying y = 2x + 5 and two formulas simultaneously, we can get
4X*X+（20+2p）X+25=0
or
y*y - 4qx -10q=0
Abscissa X. = (x1 + x2) / 2
I don't have a pen and paper

How to calculate cylinder diameter, length and pressure

Check the mechanical design manual, there is a detailed design formula. The selection of cylinder diameter is related to the pressure. Generally, the pressure is 0.7mp, depending on how much thrust you need. If the thrust is f, the required cylinder area is s = f / P, and P is the pressure, which is 0.7mp. Calculate the diameter according to the area. Of course, in order to be safe, calculate the output thrust should be multiplied by one

Clever calculation: 1 + 3 + 9 + + 27 + 81 + 243 + 729 + 2187

1+3+9+27+81+243+729+2187
=(3+2187)+(9+81)+(27+243)+（729+1）
=2190+90+270+730
=2280+1000
=3280

How to solve 1 + (dy / DX) ^ 2 = y ^ 2
Seek y

(dy/dx)=sqrt(y^2-1) which implies:dy/sqrt (y^2-1)=dx integrate both sides:integrate (1/sqrt(y^2-1))dy = x which leads to:ln|y+sqrt(y^2-1)|=x Please pay attention to the +/- after each steps.I didnt consider this issue here.

How many tons of sand

According to the bulk density of sand, it is generally required that the bulk density of construction sand is 1350-1450kg / m3. Therefore, the weight of one cubic meter of sand can be calculated as 1.35-1.45t
I hope I can help you

Two questions about complete square formula
1. Please explain that no matter what number x, y take, the algebraic formula: the square of X + the square of Y - 2x + 4Y + 6 is a positive number
2. Given the square of X + the square of Y + 4x-6y + 13 = 0, find the value of Y degree of X

X ^ 2 + y ^ 2-2x + 4Y + 6 = (x ^ 2-2x + 1) + (y ^ 2 + 4Y + 4) + 1 = (x-1) ^ 2 + (y + 2) ^ 2 + 1 because (x-1) ^ 2 and (y + 2) ^ 2 are always greater than or equal to 0, so the value of this algebraic expression is positive if it is greater than 0 after adding 1; X ^ 2 + y ^ 2 + 4x-6y + 13 = 0 (x ^ 2 + 4x + 4) + (y ^ 2-6y + 9) = 0 (x + 2) ^ 2 + (Y-3) ^ 2 = 0 because (x + 2) ^ 2 and (