If 2 is a root of the equation x & # 178; - C = 0, what is the constant C? Can you find the other roots of the equation?

If 2 is a root of the equation x & # 178; - C = 0, what is the constant C? Can you find the other roots of the equation?

4-c=0；
c=4；
x²-4=0；
（x+2）(x-2)=0;
x1=-2,x2=2;
The other is - 2;
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It is known that the parabola y = x2 + (A-2) x-2a (a is constant and a > 0). (1) prove that there are two intersections between the parabola and the X axis; (2) let the two intersections of the parabola and the X axis be a and B respectively (a is on the left side of B), and the intersection of the parabola and the Y axis be c Y = 3x translates t units along the positive direction of Y axis. The translated line is l ', and the corresponding points of a and B are a' and B 'respectively. When t is the value, there is a point P on the line L', so that △ a 'B' p is an isosceles right triangle with a 'B' as the right side

(1) It is proved that: let y = 0, then x2 + (A-2) x-2a = 0 △ = (A-2) 2 + 8A = (a + 2) 2 (1 point) ∵ a > 0, ∵ a + 2 > 0 ∵ 0 ∵ the equation x2 + (A-2) x-2a = 0 has two unequal real roots; the parabola and X-axis have two intersections (2 points) (2) let y = 0, then x2 + (A-2) x-2a = 0

12. The length of a square is x meters. If one side of the square is reduced by 1.2 meters and the other side is reduced by 1.5 meters, the area of the rectangle is 14.4 square meters less than that of the square________________________________________
Formula plus result

Xsquare - {(x-1.2) (x-1.5)} = 14.4
After calculation, x = 6
The square has an area of 36 square meters
The area of the rectangle is 21.6 square meters

If an asteroid circulates around the sun at a uniform speed and its orbit radius is four times the radius of the earth's revolution, then:
A. His linear velocity is twice that of the earth
B. His linear velocity is half that of the earth

From GMM / R & # 178; = MV & # 178 / R, v = √ GM / R
So V star = √ GM / R star V ground = √ GM / R ground
V star / V ground = √ r ground / R star = √ 1 / 4 = 1 / 2
B. His linear velocity is half that of the earth
correct.

Take two identical tuning forks, let the opening of the two speakers be opposite, use a thin line to hang a ball of plastic ball (or table tennis ball) and lightly touch the fork on the left, use the hammer to hit the tuning fork on the right to make it vibrate and sound, observe the reaction of the tuning fork and foam plastic ball on the left, you will find that the foam ball is sprung up, and then hold the fork fork on the right fork to stop the vibration. We will hear the sound of the tuning fork on the left. What conclusions can we draw from the experiment?

Sound has energy
Sound is produced by the vibration of objects

The length of a rectangle is eight thirds of its width. If the width is increased by 10 cm, the rectangle will become a square. What are the area and perimeter of the rectangle?

If the width of a rectangle is x cm, the length is 8 / 3x,
According to the meaning of the title:
X+10=8/3X
3X+30=8X
5X=30
X=6,
The side length of the square: 8 / 3x = 16,
Square area: 16 square = 256 square centimeters,
Square perimeter: 4 × 16 = 64 cm

How can 14 / 15 * 16 be easily calculated?

14/15*16
=14/15*(15+1)
=14/15*15+14/15*1
=14+14/15
=14 and 14 / 15

Given the function f (x) = A-1 / | x |, if the value range of function y = f (x) on [M, n] is [M, n] (m ≠ n), find the value range of real number a

1) Finding monotone interval of function
When x > 0 or x0, f (x) = A-1 / x increases monotonically
When x0, f (m) = m and f (n) = n and m2 or a = 0}
Package pair

How many biggest circles can be cut out on a rectangular paperboard 20 cm long and 2 cm wide? What is the area of each circle? What's the area of the rest?

The diameter of the largest circle cut is 2, and the largest circle can be cut out: 20 ／ 2 = 10 (pieces), 3.14 × (2 ／ 2) 2 = 3.14 (square centimeter), 20 × 2-3.14 × 10, = 40-31.4, = 8.6 (square centimeter). A: 10 largest circles can be cut out, the area of each circle is 3.14 square centimeter, and the area of the remaining part is 8.6 square centimeter

Add four operation symbols between the five 5S to make the result equal to 100

5*5*5-5*5