A cuboid glass container with a bottom area of 96 square centimeters and a height of 10 centimeters contains 5 centimeters of water. Now, an iron bead is completely immersed in water In the above, the water level rises by 2 cm. What's the volume of this iron bead? At least a few of these iron beads must be placed before the water overflows the glass container?

The volume of iron bead = the volume of rising water surface after adding iron bead
The volume of iron bead is 96 × 2 = 192 (cm3)
At least the number of iron beads is: (10-5) △ 2 = 2.5 ≈ 3 (pieces)

In a rectangular glass container, the bottom area is 120 square centimeters from the inside. There is water in the container. The water surface is 11 centimeters high. After a cone with a bottom circumference of 31.4 cm is submerged, the water surface rises to 13 centimeters. How many centimeters is the height of the cone? (keep one decimal place)

The volume of cone: 120 × (13-11) = 240 (cubic centimeter), the bottom radius of cone: 31.4 △ 3.14 △ 2 = 5 (centimeter), the height of cone: 240 × 3 △ 3.14 × 52, = 720 △ 78.5, ≈ 9.2 (centimeter); answer: the height of cone is about 9.2 centimeter

75 + 77 + 79 + 81 + 83 + 85 = () times（

160 times 3

The polynomial after the product of a binomial with X and X2 + X + 1 does not contain a first-order term. Please write such a first-order binomial______ ．

Let the binomial be x + A. according to the meaning of the question, we can get: (x + a) (x2 + X + 1) = X3 + (a + 1) x2 + (a + 1) x + A. according to the result, we can get a + 1 = 0, that is, a = - 1. Then a binomial satisfying the meaning of the question can be X-1. So the answer is: X-1

In a store, the purchase price of a product is 2000 yuan per piece. If the product is sold at 80% of the price, the profit of each product will be reduced by 60%______ Yuan

Suppose the price of goods is x yuan, x-80% x = 60% (x-2000) x = 3000, so the price of goods is 3000 yuan

(200+199—198+197-196+...+3-2+1)/5=?

(200+199-198+197-196+...+3-2+1)/5
=(200+(199-198)+(197-196)+...+(3-2)+1)/5
=(200+99+1)/5
=300/5
=60

Why do arccos (1 / | x |) need absolute value
Indefinite integral of 1 / [x * (x * x-1) ^ 0.5]

This integral is very simple. I don't think it's necessary to say. The key is to use x = sect for trigonometric substitution. How should t be expressed when we replace it? Because we don't use arcsecx function, of course t can't be expressed as arcsecx. This function has never been defined. In indefinite integral, when we use x = sect for trigonometric substitution, we agree that

3.56×38.5+0.7×356+9.15×35.6．

3.56×38.5+0.7×356+9.15×35.6=35.6×3.85+70×35.6+9.15×35.6=35.6×（3.85+70+9.15）=35.6×83=2954.8．

One third, two-quarters, three-quarters, and four quarters. What's the number, n?

Five out of ninety-nine
Molecule: the (n-1) power of n * (- 1)
Denominator: (2n + 1) * (2n-1)

The square of (a + 1 / 2) + |b-2a | = 0, a =?, B =?

If one is greater than 0, then the other is less than 0
So both are equal to zero
So a + 1 / 2 = 0, b-2a = 0
therefore
a=-1/2
b=2a=-1