The length of a round pool is 62.8 meters. How many square meters does the pool cover?

The length of a round pool is 62.8 meters. How many square meters does the pool cover?

62.8 ﹣ 3.14 ﹣ 2 = 10 (meters), 3.14 × 102 = 314 (square meters); answer: this pool covers an area of 314 square meters

The area of a round garden is 4 / 4 hectare, in which three kinds of flowers are planted. Peony accounts for 2 / 5, lily for 1 / 20, and the rest are roses. Roses account for the total area

Rose in total = 1-2 / 5-1 / 20 = 9 / 20

Find the tangent equation and normal equation of the point (2, in2) on the curve y = INX

The derivative y '= 1 / x, so the slope k = 1 / 2, corresponding to the tangent equation y-ln2 = 1 / 2 (X-2); the corresponding normal slope k = - 2 (because KK = 1), the normal equation y-ln2 = - 2 (X-2);

How to solve X-15 7x = 25 14
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X-7 / 15x = 14 / 25, that is 8 / 15x = 14 / 25, x = 14 / 25 * 15 / 8 = 21 / 20

Given that positive real numbers x, y, Z satisfy 2x (x + 1y + 1z) = YZ, then the minimum value of (x + 1y) (x + 1z) is______ ．

∵ positive real numbers x, y, Z satisfy 2x (x + 1y + 1z) = YZ, ∵ x2 + X (1y + 1z) = 12yz, ∵ (x + 1y) (x + 1z) = x2 + X ((1y + 1z) + 1yz = 12yz + 1yz ≥ 212 = 2. If and only if YZ = 2, the minimum value 2 is obtained

The difference between a number and its reciprocal is 27. How many such numbers are there?

A-1 / a = 27 solve the equation (a ^ 2-27a-1) / a = 0. Because a is not equal to 0, we can judge whether the molecule can be equal to 0. There are two roots for 0, which are (733) / 2 under 27 + / - roots

Let XY satisfy 2x + y ≥ 4, X-Y ≥ - 1, x-2y ≤ 2, then the minimum value of (x-1) 2 + (y + 1) 2 is

Formula 1 + 2 gives x > = 1, formula 3 times - 1, and formula 2 gives Y > = - 3, 2 (x + y) > = - 4

In the interval [0,2], take two numbers a and B randomly, then the probability of zero free function f (x) = x2 + ax + B2 is______ ．

Take two numbers a and B randomly in the interval [0, 2], then the plane area corresponding to (a, b) is shown as the rectangle in the figure below: if the function f (x) = x2 + ax + B2 has no zero point, then a2-4b2 < 0, that is, the plane area corresponding to | a | and | 2B | is shown as the shadow in the figure below: ∵ s rectangle = 2 × 2 = 4S, shadow = 4-12 × 2 × 1 = 3 ∥ function f (?)

Let a and B be the intersection of the straight line 3x + 4Y + 2 = 0 and the circle x2 + Y2 + 4Y = 0, then the equation of the vertical bisector of the line AB is

Circle x2 + Y2 + 4Y = 0
x^2+(y-2)^2=4
So the center of the circle (0,2)
The slope of the straight line is - 3 / 4, and the slope of its vertical bisector is 4 / 3
So the equation of vertical bisector is
y-2=k(x-0)
That is 4 / 3x-y + 2 = 0
That is 4x-3y + 6 = 0

Given that the quadratic function y = f (x) satisfies f (2-x) = f (2 + x), then the symmetry axis of the quadratic function is?

Let y = ax & # 178; + BX + C
f(2-x)=f(2+x)
a(2-x)²+b(2-x)+c=a(2+x)²+b(2+x)+c
b=-4a
Axis of symmetry x = - B / 2A = 2