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1. In our daily life, we often estimate the objects around us. The following four options are the results of a student's estimation. What do you think is the most unreasonable is -------- - (& # 160; & # 160; & # 160; & # 160;) &#A. generally speaking, the body temperature is 37 ℃. B. the speed of the champion of 100 meter race in the sports meeting is 54 km / h &#C. the weight of an egg is about 50g. D. the volume of a bottle of Wahaha Purified water is about 600ml
B the top speed of the 100 meter race is about 11 meters per second, that is 39 km / h. It is impossible to reach 54 km / h
What forces are acting on the two wheels in cycling and the direction of action of the forces are pointed out
Gravity, elasticity and friction
The friction between the front and rear wheels is different when riding and pushing
The friction of the cart is opposite to the direction of motion
When riding a bicycle, the rear wheel is the driving wheel, and the friction force is the same as the moving direction. The friction force of the front wheel is opposite to the moving direction
Given sin α = 2cos α, find Sina + 5cosa / - 2cosa + Sina
sina+5cosa/-2cosa+sina
From the known formula, Tan α = 2
Divide the numerator and denominator of the formula by cos α to get the formula of Tan α, and its result value can be seen from the above
Try to find the connection between the known and the unknown
Bracket x plus 1 times bracket x plus 3 times bracket x plus 5 times bracket x plus 7 minus 20
The original formula = [(x + 1) (x + 7)] [(x + 3) (x + 5)] - 20 = (x ^ 2 + 8x + 7) (x ^ 2 + 8x + 15) - 20 = (x ^ 2 + 8x + 7) ^ 2 + 8 (x ^ 2 + 8x + 7) - 20 = (x ^ 2 + 8x + 7 + 10) (x ^ 2 + 8x + 7-2) = (x ^ 2 + 8x + 17) (x ^ 2 + 8x + 5) the evaluation point [satisfied] in the upper right corner of the client can be
When m takes what value, the univariate quadratic equation (m-2) x ^ 2 + (2m + 1) x + m-2 = 0
(1) There are two unequal real roots
(2) There are two equal real roots
(3) There is no real root
Δ=(2m+1)^2-4(m-2)(m-2)=4m^2+4m+1-4m^2+16m-16=20m-15
When Δ > 0, there are two unequal real roots
20m-15>0
m>3/4
When Δ = 0, there are two equal real roots
20m-15=0
m=3/4
Δ
If the image of the inverse scale function y = K / X is in the first and third quadrants, then the image of the function y = kx-3 passes through a-234 quadrant b-223 quadrant c-224 quadrant
Quadrant d-134
The solution consists of the inverse scale function y = K / X of the image in the first and third quadrants
K > 0
So the image of the first-order function y = kx-3 passes through the quadrant one three four,
So choose D
(- 2) + 4 + (- 6) + 8 + (- 10) + 12 +. + (- 98) + 100
(-2)+4+(-6)+8+(-10)+12+.+(-98)+100
=[(-2)+4]+[(-6)+8]+[(-10)+12]+.+[(-98)+100]
=2*25
=50
8x + 5x = what is the solution of this equation?
This is not an equation. It turns out to be 13X
A focal point F1 (3,0) of ellipse C is known, and the maximum distance from point to point F1 on ellipse C is 8. Find the standard equation of ellipse C
According to the formula of focal radius, the distance from point to point F1 on ellipse C = a-ex
The maximum distance from point to point F1 on ellipse C is x = - A
Distance = a-ex = a + C = 8
So a = 5
b^2=16
The standard equation of ellipse C is x ^ 2 / 25 + y ^ 2 / 16 = 1
Find 1,0, - 3,0,5,0, - 7 A general formula of this sequence is possible
The general formula is as follows:
=((n-INT(n/2)*2)*(-1)^INT(n/2))*n
In Excel, select column a, select menu insert - name - definition, enter n in the definition name dialog box, and click OK;
Enter 1, 2, 3,... In column a
Copy the formula = ((n-int (n / 2) * 2) * (- 1) ^ int (n / 2)) * n to column B, and compare it with column a 1, 2, 3 In the corresponding cell, the calculation result can be obtained
RELATED INFORMATIONS
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