The solution of x ^ 2 - 2x + 5 = 0 is complex

The solution of x ^ 2 - 2x + 5 = 0 is complex

x1=1+2i x2=1-2i

Factoring 2x ^ 2 + 2x + 3 x ^ 2-x + 1 in complex number
2X ^ 2 + 2x + 3 x ^ 2-x + 1

2X ^ 2 + 2x + 3 let 2x ^ 2 + 2x + 3 = 0, the solution is x = [- 1 ± (√ 5) I] / 2, so the original formula = {2x - [- 1 + (√ 5) I]} {X - [- 1 - (√ 5) I / 2} = [2x + 1 - (√ 5) I] {x + 1 / 2 + (√ 5) I / 2} x ^ 2-x + 1 Let x ^ 2-x + 1 = 0, the solution is x = [1 ± (√ 3) I] / 2, so the original formula = [X-1 / 2 - (√ 3) I /

Calculation questions: 1, (2 / 15-1 / 12) × 21-4 / 12, 5 / 12 / 6 / 5 + 1 / 4, 3 / 8 × 24 / 4 / 9
4. (2 / 5 + 2 / 3-4 / 15) × 305, 2 / 5 × 13 / 7 + 13 / 6 × 40%
6. 4 - [(2 / 5 + 3 / 5) △ 1 / 2]

1.=(1/20)*21-1/4=20/21-1/4=4/5
2,=1/2+1/4=3/4
3.=9*(4/9)=4
It's so simple. Let's count the rest

Draw the following points a (2,1), B (0,1), C (- 4,3), D (6,3) in the plane rectangular coordinate system, and connect them with line segments to form a four? D
Draw the following points a (2,1), B (0,1), C (- 4,3), D (6,3) in the plane rectangular coordinate system, and connect them with line segments to form a quadrilateral ABCD
(1) Quadrilateral ABCD is what special quadrilateral
(2) Find a point P in the quadrilateral ABCD so that △ APB, △ BPC, △ CPD, △ APD are isosceles triangles. Please write the coordinates of point P

Remember ` 1, because a (2,1), B (0,1), C (- 4,3), D (6,3) so BC = ad = 2 times the root, 5ab is parallel to CD, BC is not parallel to ad, so ABCD is trapezoid, so trapezoid ABCD is isosceles trapezoid 2, make the vertical line of AB, intersect CD to e, AB to F, because AB = 2, EF bisects AB vertically, so AF = BF = 1, AE = be, because a, B, C

1 / 5 - [] equals 1 / 30

1/5-1/30=1/6
So 1 / 5 - [1 / 6] equals 1 / 30

The first is x + y + 5 = 0. The second is 3x-2y = 0
How do you get the second one

If the intercept is equal, you should pay attention to the case that the intercept is 0
This is the fallible point of the problem
If the intercept is 0
Let y = KX
If (- 2, - 3) is brought in, k = 3 / 2
So the equation is y = 3 / 2x
That is, 3x-2y = 0
If the intercept is not zero
Let X / A + Y / a = 1
If (- 2, - 3) is brought in, a = - 5
So the equation is: x + y + 5 = 0

The minimum positive period of y = (SiNx + cosx) / (COS SiNx) is

The molecular denominator is divided by cosx
y=(1+tanx)/(1-tanx)
So the minimum positive period is the period of tangent function, that is t = π

The line y = - 2x-1 intersects with the line y = 3x + m at a point in the third quadrant, and the value range of M is calculated
A-1

There are two linear equations
-2x-1 = 3x + m, solve x = - (M + 1) / 5, and then bring x into the linear equation, y = 2 (M + 1) / 5-1 = (2m-3) / 5,
∵ the line y = - 2x-1 intersects the line y = 3x + m in the third quadrant
∴x

It is proved that the square-2x of function f (x) = x is an increasing function in the interval (1, + ∞)

Definition: if x > y, f (x) > F (y) holds in the domain of F (x), then the function is an increasing function
It is proved that f (x + 1) - f (x) = (x + 1) & # 178; - 2 (x + 1) - X & # 178; + 2x = 2x-1 when x belongs to (1, + ∞)
Because x > 1, so (2x-1) > 0, that is f (x + 1) > F (x), and (x + 1) > x, so the function is an increasing function

From the inside, what is the volume of the cube box with the edge length of 1 decimeter? How many liters of liquid can it hold

1 × 1 × 1 = 1 (cubic decimeter)
1 cubic decimeter = 1 liter
Volume 1 cubic decimeter, can hold 1 liter of liquid