What kind of books does x stand for

What kind of books does x stand for

Books on Environmental Science and Safety Science

What idioms are used to express things

Magnificent, depicting the dragon and embroidering the Phoenix, behemoths

Who knows more than five words for books?
More than five words for books,

Book -- Book
Manual
Magazine
Dictionary
Encyclopedia

It is known that a = a + 2, B = a2-a + 5, C = A2 + 5a-19, where a > 2. (1) prove that B-A > 0, and point out the size relationship between a and B; (2) point out which is bigger between a and C? Give reasons

(1) B-A = (A-1) 2 + 2 > 0, so b > A; (2) C-A = A2 + 5a-19-a-2, = A2 + 4a-21, = (a + 7) (A-3). Because a > 2, so a + 7 > 0, so when 2 < a < 3, a > C; when a = 3, a = C; when a > 3, a < C

27.3 * 37.3-17.3 * 37.3

27.3*37.3-17.3*37.3=（27.3-17.3）*37.3=10*37.3=373

When m is a real number, the sum of the squares of the two real roots of the equation x square - 2mx + (M + 2) = 0 is greater than 2

If the equation has roots, it means that the Weida theorem holds, so if X1 + x2 = 2m, X1 * x2 = m + 2, then X1 ^ 2 + x2 ^ 2 = (x1 + x2) ^ 2-2 * X1 * x2 > 2, the solution is m

There are three numbers a, B and C. number a is one third of the sum of two numbers B and C. number B is one half of the sum of two numbers B and C. how much is the sum of three numbers a, B and C?

The number B is one-half of the sum of the two numbers B and C, that is, B equals C, and the number a is one-third of the sum of the two numbers B and C. Since B equals C, a is 1 / 3 of B or C multiplied by 2 = 2 / 3. Therefore, the total share of a, B and C is 1 + 1 + 2 / 3 = 2 and 2 / 3 = 8 / 3

The carriage of a freight car is a cuboid, its length, width and height are 4m, 2M and 3M respectively (measured from the inside) filled with a car of sand
After unloading, pile the sand into a cone with a height of 2m. What is the bottom area of the cone?

Set the bottom area as S
4X3X2=S X 2 X (1/3)
S = 36

What's four fifths divided by 0.8? Thank you

0.8 = four fifths
Four fifths divided by four fifths = 1

Find the sequence - 1,4, - 7,10 The sum of the first n terms of (- 1) ^ n * (3n-2)

If n is even,
Sn=3n/2
If it's odd
Sn=-1-3(n-1)/2
=-(3n-1)/2
therefore
Sn=(-1)^n*(6n-1)/4+1/4