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Point P (x, y) is a point in the plane rectangular coordinate system. If XY equals 0, then the position of point P is___
On the axis
Build a 7.2m wide and 20cm thick cement road. If 14.4m3 of concrete is mixed, how many meters of road can be paved?
14.4 / 7.2 / 0.2 = 10m;
It can pave a 10 meter road
Given a ^ 2 + B ^ 2 = 1 and a (- 1 / 2,1), then the minimum value of function y = 2A + (b ^ 2) / [(a + 1) ^ 2] is?
RT
b^2=1-a^2=(1-a)/(1+a)
==>
y=2(a+1)+ (1-a)/(1+a) -2
=2(a+1)+2/(1+a)-3
Then because a + 1 ∈ (1 / 2,2)
So. A + 1 = 1 is the minimum, ((a + 1) + 1 / (a + 1) > = 2, take the equal sign when a + 1 = 1);
So the minimum value of Y is 1,
Attention upstairs. Do you get an equal sign?
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? (π≈ 3, unit: M & # 178;)
S=πr²=3×（10^-6÷2）²=7.5×10^-13（m²）
Hope to adopt
Please give a brief description of the changes in the mass and density of the gas packed in a closed container when its volume is compressed
According to the formula v = MP (P density), the mass in the container will not change, but only the density
If a set of data x1, X2, X3, x4 The average of XN is 2003, so the average of X1 + 5, X2 + 5, X3 + 5, X4 + 5,... Xn + 5 is
2003+5=2008
The first answer, how about a score?
The parabolic equation can be solved when a chord is y = 2x + 5 and the abscissa of the midpoint of the chord is - 3
If it is a standard equation:
(1) If the equation is the square of y = 2px
Let the midpoint be o, and the intersection of the chord and the parabola be a (x1, Y1), B (X2, Y2)
Square of Y1 = 2px1 square of y2 = 2px2
We obtain (y1-y2) * (Y1 + Y2) = 2p (x1-x2) and point O (- 3, - 1), so Y1 + y2 = - 2,
And (y1-y2) / (x1-x2) = 2, so: P = - 2, that is, the square of y = - 4x
(2) If the square of x = 2PY, the same is true
The diameter of the cylinder is 125mm, the shaft is 12mm, and the air source pressure is 0.6MPa. How many n meters is the thrust of the cylinder calculated? What is the calculation formula
Alone in this, to accommodate the broad sea;
There are three or two ways of understanding,
Play sun's tender heart
Millionaires fall in the bull market overnight
Why is he so busy
Torrential rain, pregnant with a brilliant Yang;
1-1/3-1/9-1/27-1/81-1/243-1/729-1/2187
1-1/3-1/9-1/27-1/81-1/243-1/729-1/2187=1-(1/3+1/9+1/27+1/81+1/243+1/729+1/2187)=1-(1/3)*[1-(1/3)^7]/[1-(1/3)]=1-(1/3)*[1-(1/2187)]/(2/3)=1-(1/2)*(2186/2187)=1094/2187
Solving DX / x ^ 2 = dy / y ^ 2
∵dx/x^2=dy/y^2
==>-1 / x = - 1 / y + C (C is constant)
==>1/x-1/y+C=0
The general solution of the original equation is 1 / X-1 / y + C = 0
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