On the equation root x ^ 2-1 + root x-k = 0 of X, if there is a real root, then the value of K is emergency

On the equation root x ^ 2-1 + root x-k = 0 of X, if there is a real root, then the value of K is emergency

The root sign is "0", so x = k, x ^ 2 = 1, k = 1 - 1

Given that the quadratic equation (ab-2b) x & sup2; + 2 (B-A) x + 2A AB = 0 has two equal real roots, then 2 / A + 2 / b =?
Before tonight (⊙ o ⊙)
There's another one.
Given that x, y, Z satisfy x + y + 2Z = 1, X & sup2; + Y & sup2; + 6Z + 1.5 = 0, find the value of X, y, Z

(1) Derivation of the equation f (x) = (ab-2b) x & sup2; + 2 (B-A) x + 2A ab
The equation has two equal real roots
f（x')=2(ab-2b）+2(b-a)=0
Ab-b-a = 0 divided by ab
1/a+1/b=1
Then 2 / A + 2 / b = 2

6 11 13 7 how to calculate 24 o'clock?
There are also 8 7 11 13 2 13 5 10 8 9 13 6

(11+13)*(7-6)
(11+13)*(8-7)
()
8+9-6+13

Let P (x, y) be any point on the circle x2 + (y + 4) 2 = 4, then the maximum value of (x − 1) 2 + (Y − 1) 2 is______ ．

According to the meaning of the question, (x − 1) 2 + (Y − 1) 2 represents the distance between the point P (x, y) and (1, 1) on the circle, then its maximum value is the distance between the center of the circle (0, - 4) and (1, 1) plus the radius, that is, the maximum value of (x − 1) 2 + (Y − 1) 2 is: (0 − 1) 2 + (− 4 − 1) 2 + 2 = 26 + 2

The volume of the balloon floating in the air is 1500m ^ 3, and the known air density is 1.29kg/m ^ 3
From this, we can know the mass of the air emitted by the hydrogen balloon and the buoyancy n? (G is 10N / kg)

1500*1.29=1935kg
The buoyancy is 19350n

It is known that the length of the bottom side of the regular hexagonal prism is 10 cm and the height is 15 cm?

6

If the point m (x, y) satisfies x + Y > 0 and XY ≥ 0, then the point m may be in the plane rectangular coordinate system?

If XY ≥ 0, x > 0, Y > 0 or x0, Y > 0
That is, point m may be in the first quadrant of the plane rectangular coordinate system

Build a cement road with a width of 3.6 meters and a thickness of 20 cm. If 7.2 cubic meters of concrete is mixed, how many meters can it be paved?

20 cm = 0.2 m, 7.2 △ 3.6 × 0.2, = 7.2 △ 0.72, = 10 m; a: it can be paved for 10 m

If a > 0, b > 0, 2A + B = 1, then the minimum value of 1A + 1b is 1___ ．

∵ a > 0, b > 0, 2A + B = 1, ∵ 1A + 1b = (2a + b) (1a + 1b) = 3 + 2Ab + BA ≥ 3 + 22ab · Ba = 3 + 22, if and only if B = 2A = 2-1, the equal sign is taken. The minimum value of ∵ 1A + 1b is 3 + 22

Silk is the thinnest natural fiber. Its cross-sectional diameter is about 10um (1um = 10 to the - 6th Power M). What is its cross-sectional area? (unit: square centimeter)

Area = 3.14 * 5um * 5um = 78.5 * 10 ^ - 12m2 = 7.85 * 10 ^ - 7cm2
The - 6 power of 1um = 10 m = 10 ^ - 4cm
Area = 3.14 * 5um * 5um = 78.5 * 10 ^ - 8cm2 = 7.85 * 10 ^ - 7cm2