When light passes through a glass plate, its intensity should be reduced by 1 / 10, and the intensity of light should be reduced to less than 1 / 3 of the original. At least such a glass plate; (answer: 11) How to solve it with log?

Set X Block
Then 1 piece is 1-1 / 10
The second piece is (1-1 / 10) * (1-1 / 10) = (1-1 / 10) ^ 2
and so on
X Block weakened to (1-1 / 10) ^ x < 1 / 3
0.9^x<1/3
0<0.9<1
So log0.9 (x) is a subtractive function
So take the logarithm with the base of 0.9 on both sides, and the unequal sign changes direction
x> Log0.9 (1 / 3) is approximately equal to 10.5
So x min = 11
So at least $11

(log2 9)/(log2 8) = 2/3(log2 3)

log(2,9)=log(2,3^2)=2log(2,3)
log(2,8)=log(2,2^3)=3log(2,2)=3
So (log2,9) / (log2,8) = 2 / 3 (log2,3)

Senior one mathematics (calculation of log) Given 2lg [(X-Y) ÷ 2] = lgx + lgY, find the value of log [take (3-2 root sign 2) and (x ÷ y) as the true number] See clearly!

2lg【（x-y）÷2】=lgx+lgy
That is, the square of [(X-Y) ÷ 2] = XY
The solution shows that x ÷ y is 3-2 root sign 2
Then the value of log [taking (3-2 root sign 2) and (x ÷ y) as the true number]
Yes 1

Logarithmic function formula LG (M + n) =? lg（m*n）=lgm+lgn Then LG (M + n) =?

This one without formula is the simplest

What is the idiom used to describe "fire in July"? 3Q A. Hot summer B. summer goes to autumn C. spring goes to summer D. autumn goes to winter

Choose B "July Liuhuo" to say "July Liuhuo, September clothes" in the book of songs · national wind · CHENFENG. Its real meaning is not that it is hot in July, but is closely related to an astronomical phenomenon, that is, the weather turns cool in July of the summer calendar (lunar calendar). "July" refers to July of the summer calendar; "Flow" refers to moving and falling; "Fire" refers to the star name "big Mars" (not Mars orbiting the sun), i.e. Antarctica. "Big Mars" is a famous red giant star, which can emit fire red light. It is located in the due south at the dusk of may in the summer calendar every year, and its position is the highest. At the dusk of July in the summer calendar, the position of big Mars gradually descends from the midheaven to the west, "knowing that the heat is receding and autumn is coming". People call this phenomenon "floating fire in July" Therefore, the real meaning of "July Liuhuo" means that in July of the summer calendar, the weather gradually turns cool. At dusk, you can see the great Mars falling from the West. It is said that there was a Chen (b) under King Cheng of Zhou 3000 years ago ī n) The state of Chen was the birthplace of the agricultural culture of the Zhou nationality long ago. At that time, the calendar was not perfect, and it was necessary to watch the stars to guide agricultural activities. At the end of summer every year, a red star named fire, alpha Scorpio, scorpion heart, appeared in the due south sky. Based on the ancestral observation experience, farmers knew that summer was over and autumn was coming, The busiest autumn harvest season of the year has come. It is a few days in a hurry. At the same time on autumn Eve, the farmer looks at the southern sky again and finds that the fire has moved westward and fallen more than a few days ago. A few days later, it has moved westward and fallen even more. At the same time a month later, looking at the southern sky, the fire has moved and fallen to the western horizon, too low, covered in clouds and clouds, hidden in mountains and invisible. Ladies and gentlemen, this process is called "July flowing fire" There must be no two in this solution. The water bows its head and says it flows. The fire is also flowing when it moves westward. Fire here has its own connotation and its meaning is special. It specifically refers to alpha Scorpio, which was called Antares in ancient Chinese astronomy. It is by no means the fire of "the red sun is burning like fire". If you look at the text, you will laugh. The first two sentences of "flowing fire in July and giving clothes in September" are the first two sentences of the wind of July. The first sentence is the introduction, The weather is getting colder and colder. It's time to sew cold clothes. Another thing to say is that the lunar calendar was used 3000 years ago. It can be known that July was now August. If you want to observe today, you have to wait until September of the Gregorian calendar

What are the idioms that describe very strictly? It's best to describe that others treat themselves very strictly and urgently!

Set an example, be strict with yourself, do everything personally, be diligent and thrifty, serve the public and be a modest gentleman

When light passes through a glass plate, its intensity should be reduced by 1 / 10, and the intensity of light should be reduced to less than 1 / 3 of the original. At least such a glass plate; (answer: 11) How to solve it with log?