I asked the math question: When 5% and 40% sugar water are mixed, 140 g sugar water containing 30% sugar should be prepared. How many grams of each of the two solutions should be taken?

5%x+(140-x)×40%=140×30%
x=40
140-40=100

There are three kinds of salt water: A, B and C. the salt content of a salt water is 4%, B salt content is 5%, and C salt content is 6%? Write the formula clearly and explain it by the way

In order to obtain 60 kg salt water with 2% salt content, 60 × 2% = 1.2 kg, water demand 60-1.2 = 58.8 kg x kg, salt content 1.2 kg x 4% = 1.2 x = 30 kg, 30 kg a, is difficult to be distilled by low concentration salt

Find the real number solution of the equation system: ① x + y = 2 ② xy-z ^ = 1

From 2, xy-z 2 = 1,
z²=xy-1
∵z²≥0,
∴xy≥1③,
From (1) x + y = 2,
Y = 2-x,
Substituting into 3, X (2-x) ≥ 1
x²-2x+1≤0
(x-1)²≤0
∴x=1,
They are replaced by ① and ② respectively,
Y = 1, z = 0

If the blood type of the recipient and the donor does not match, agglutination will occur after blood transfusion A red blood cell B white blood cell C plasma D platelet If an adult weighs about 80 kg, his total blood volume is about () a2.3.5 b5.6.5 c7.8.5 d10~12

The first question is a
The second question is also a

A bottle of 0 ℃ water, put in a container, pumping out the air inside, what will happen to the situation? The container is made of glass, so I asked directly, shouldn't freezing not occur when freezing point is lowered?

It will freeze
For water, a substance with larger volume after solidification, the smaller the pressure is, the smaller the melting point will be. Therefore, when the external pressure decreases, the melting point of water will be higher than 0 ℃, so it will freeze, The solid vapor pressure rises more at the same temperature, so the freezing point will be higher than 0 ℃

It's not difficult to ask junior high school questions My friend always asks me _ her with her homework. A.assist B.to assist C.assisting D.assisted Correct answer B My mother __ me to assist her with the housework. A.asked B.asked for C.wants D.please Correct answer B I'm not sure about the two questions. Please teach me

1 ask sb.to My friend often asks me to help her with her homework
My mother asked me to help her with the housework

Ask math questions about high school collections Given the complete set u = R, set a = {X / x square + 4ax-4a + 3 = 0}, B = {X / x square - (A-1) x + a square = 0}, C = {X / x square + 2ax-2a = 0}, if at least one of a, B, C is not an empty set, find the value range of real number a

At least one set is not an empty set, so obviously the proposition of "no" is simple, and the "no" proposition is all empty set

It is known that the radius of the base of a cone is R and its height is 3R. Among all its inscribed cylinders, the maximum value of the total area is______ .

If the radius of the base of the inscribed cylinder is r, the height is h, and the total area is s, then there is 3R − H
3R＝r
R
∴h=3R-3r
∴S=2πrh+2πr2
=-4πr2+6πRr
=-4π（r2-3
2Rr）=-4π（r-3
4R）2+9
4πR2
When r = 3
When 4R, the maximum value of S is 9
4πR2．
So the answer is: 9
4πR2．

Ask about geometry, about cones If the length of the conical generatrix is r, and the sinusoidal value of the center angle of the side expanded view is √ 3 / 2, then the height is? Why are the two values √ 35 / 6R and 2 √ 2 / 3R I only calculate the first value

The sinusoidal value of the center angle of the side expansion is √ 3 / 2
Then the center angle of the side expansion (sector) is 120 degrees or 60 degrees
When the center angle of the circle is 120 °, the radius of the bottom is R / 3 and the height of the cone is √ 3 / 2R
When the center angle of the circle is 60 °, the radius of the bottom is R / 6 and the height of the cone is √ 35 / 6R

Asking geometric proof questions As shown in the figure, in the parallelogram ABCD, the angle DAB = 60 ° and the points E and F are respectively on the extension line of CD and AB, and AE = ad, CF = CB If the "angle DAB = 60" of the known condition is removed, is the above conclusion still valid? If yes, please write the proof process; if not, please explain the reasons There must be a reason This topic is complete!

Because you assume that the angle DAB = 120 ° CD ∥ AB, it is easy to know that the angle EDA is also 120 ° and that △ EDA is an isosceles triangle because AE = ad, so the angle AED = angle EDA, so the conclusion is drawn. Have you ever seen two triangles with obtuse angles?

I asked the math question: When 5% and 40% sugar water are mixed, 140 g sugar water containing 30% sugar should be prepared. How many grams of each of the two solutions should be taken?