There is a polynomial x to the 10th power minus x to the 9th power y to the 8th power of X to the 2nd power of y to the 7th power of X to the 3rd power of Y According to this rule, what is the seventh term? What is the last term? What is the last term of this polynomial? (by the way)

First judge the symbol, obviously one positive and one negative cross
Then judge the letters: X and y, the total number of times is 10, remain unchanged
The index of obvious x decreases from 10 to 0
The exponent of Y increases from 0 to 10
So the seventh term is: the fourth power of X and the sixth power of Y
The last term is the 11th term of the polynomial
The law
The letter: X and y, the total number of times is 10, unchanged
If the rule is expressed by an expression containing N, then: (- 1) to the (n + 1) power * x to the (11-n) power * y to the (n-1) power
[where n is a positive integer of 1 ≤ n ≤ 11]

It is proved that the 10th power of polynomial 7 - the 9th power of 7 - the 8th power of 7 can be divisible by 41

A common factor 7 ^ 7 can be proposed
Namely
7^10 - 7^9 - 7^8
= 7^8 × ( 7^2 - 7 - 1 )
= 7^8 × ( 49 - 7 - 1 )
= 7^8 × 41
That is, the original polynomial can be divisible by 41

There is a polynomial a10-a9b + a8b2-a7b3 + Write according to this rule (1) Write the sixth and last item; (2) How many times and terms is this polynomial?

(1) Item 6: - a5b5, last item: B10;
(2) Ten times and eleven terms

If the square of the polynomial x + the square of 2kxy-3y + X-10 does not contain XY term, find the value of the third power-1 of K

Without XY term, the coefficient of this term is 0
So 2K = 0
K=0
So the third power of K is - 1 = - 1

If a = 1.6 × 109, B = 4 × 103, then A2 △ 2B = () A. 2×107 B. 4×1014 C. 3.2×105 D. 3.2×1014

a2÷2b，
=（1.6×109）2÷（8×103），
=（2.56×1018）÷（8×103），
=3.2×1014．
Therefore, D

It is known that the energy obtained from the sun in a year is equivalent to the energy generated by burning 1.3 * 10 8-kg coal on a land area of 1 square km, On the land of the sixth power of 9.6 * 10 in China, the energy obtained from the sun in one year is equivalent to the energy produced by a * 10 n-th power kg coal. Calculate the values of a and n

9.6*10^6*1.3*10^8
=1.248*10^15
a=1.248
n=15

It is known that the energy obtained from the sun in a year is equivalent to the energy generated by burning 1.3 × 10 8 kg coal on a land area of 1 m square meters

0

In China, the energy gained in one year is equivalent to that generated by 9.6 * 10 ^ 6 * 1.33 * 10 ^ 8 kg coal
The above formula = 12.768 * 10 ^ 14 kg coal energy
768, n = 14

It is known that in one square kilometer of land, the energy obtained from the sun in one year is equivalent to the energy generated by burning 1.3 × 10 8-kilogram coal On 9.6 million square kilometers of land, the energy obtained from the sun in ten years is equivalent to the energy generated by burning several kilograms of coal

The eighth power of 1.3 × 10 × 9.6 million × 10
=The 14th power of 124.8 × 10
=1.248 × 10 to the 16th power kg

It is known that the energy obtained from the sun in one year on the land of 1 km ^ 2 is equivalent to the energy generated by burning 1.3 * 10 coal of the eighth power. Then, the energy obtained from the sun in a year on the land of 9.6 times 10 is equivalent to burning a × 10 ^ n kg coal (the result retains two significant figures, 1 ≤ a < 10, n is a positive integer)

The 8th power of 1.3 * 10 × 9.6 times the 6th power of 10 = a × 10 ^ n
12.48×10^14=a×10^n
1.3×10^15=a×10^n
∴a=1.3
n=15

There is a polynomial x to the 10th power minus x to the 9th power y to the 8th power of X to the 2nd power of y to the 7th power of X to the 3rd power of Y According to this rule, what is the seventh term? What is the last term? What is the last term of this polynomial? (by the way)