There are 250 story books and science and technology books in the book corner. One ninth of them are loaned out, five more than science books. How many story books and science and technology books are there?

Suppose that the story book is x, then the science and technology book is 250-x, and there are (1-1 / 9) x left after one ninth of the story book is lent out. The equivalent relationship can be obtained from the title: (1-1 / 9) x - (250-x) = 5 (there are 5 more story books than science and technology books after one ninth of the story book is lent out). The solution is x = 135, so the 135 story books and the science and technology book is 250-135 = 115

Storybooks are one third less than science and technology books. How many times are storybooks?

2/3

If the equation 4 ^ x-a * 2 ^ x + 4 = 0 of X has a real root in [0,2], find the value range of real number a

With the idea of separating variables
4^x-a*2^x+4=0
a*2^x=4^x+4
a=2^x+4/2^x
If there is a solution in [0,2], only the range is required
Let t = 2 ^ x, then t belongs to [1,4]
a=t+4/t,
This is the check (Nike) function. In the first quadrant, the check bottom is t = 2
Therefore, it decreases on [1,2] and increases on [2,4]
When t = 2, a = 4;
When t = 1 or T = 4, a = 5;
Therefore, the value range of a is [4,5]

There is a batch of cement on the construction site, 40% of which was transported in the first time, 25.5 tons in the second time, and 17 tons left. How many tons are there in total?

(25.5 + 17) / (1-40%) = 42.5 / 0.6 = 425 / 6 = 70 5 / 6 tons

It is known that the vertex coordinates of the parabola y = AX2 + BX + C are (4, - 1), intersecting with the y-axis at the point C (0,3), and O is the origin. (1) find the analytical formula of the parabola; (2) let the intersection of the parabola and the x-axis be a, B (a is on the left side of B), and ask whether there is a point P on the y-axis, so that the triangle with O, B, P as the vertex is similar to △ AOC? If it exists, request the coordinates of point p; if not, please explain the reason

(1) Let y = a (x-4) 2-1, (2 points) ∵ intersect Y-axis at C (0,3), (3 points) ∵ 16a-1, (3 points) ∵ a = 14, ∵ the analytic formula of parabola is y = 14 (x-4) 2-1, that is, ∵ y = 14x2-2x + 3. (4 points) (2) exists. (5 points) when y = 0, then 14 (x-4) 2-1 = 0, ∵ X1 = 2, X2 = 6, (6 points) ∵ a (2,0), B (6,0), let P (0, m), then OP = | m ∵ in △ AOC and △ BOP (1) if ∠ OCA = ∠ OBP, then △ BOP ∽ COA, ∽ OBOC = opoa, Op = 6 × 23 = 4, ∽ M = ± 4; (7 points) if ∠ OCA = ∠ OPB, then △ BOP ∽ AOC, ∽ OPOC = oboa, Op = 6 × 32 = 9, ∽ M = ± 9, (7 points) ∽ there is a point P in line with the meaning, whose coordinates are (0,4), (0, - 4), (0,9) or (0, - 9). (10 points)

The weight ratio of yellow sand in pile a and pile B is 5:4. Three tons of yellow sand are transported from pile a and four tons from pile B every day. After a few days, there are 16 tons left in pile a after pile B. how many are there

4 × 5 / 4 = 5 tons
Lucky: 16 ÷ (5-3) = 8 days
A: how many tons: 8 × 3 + 16 = 40 tons
B: how many tons: 8 × 4 = 32 tons

It is known that f (x) is an odd function defined on the interval [- 1,1], and f (1) = 1. If m, n Euro [- 1,1], M + n is not equal to zero, then [f (m) + F (n)] / (M + n) > 0, and the solution is f (4-x2) + F (x + 2) > 0

[f(m)+f(n)]/(m+n)>0
When f (m) + F (n) > 0, M + n > 0
So f (4-x & sup2;) + F (x + 2) > 0
Then 4-x & sup2; + X + 2 > 0
x²-x-6

There are two engineering teams, team a and team B. the number of team a is 30 less than that of team B. if five people are transferred from team a to team B, the number of team a is one third of that of team B. how many people are there in the two teams?

After the transfer, team a is 30 + 5 * 2 = 40 less than team B, which is 1 / 3 of team B
Then the number of team B (30 + 5 * 2) / (1-1 / 3) = 60 (people)
Team a: 60 * 1 / 3 = 20
Team a: 20 + 5 = 25
Original team B: 60-5 = 55 (people)

If real numbers x, y satisfy x + y + (X-Y) I = 2, then the value of XY is equal to

x-y=0 x=y=1
xy=1

The 30th Olympic Games in 2012 was held in London. London won the right to host the games on July 6, 2005. At that time, in the fourth round of voting, London won 54 votes, which is 8% more than Paris. How many votes is Paris less than London

Answer:
54 (1 + 8%) = 50 (votes)
54-50 = 4 (votes)
A: Paris has four votes less than London

There are 250 story books and science and technology books in the book corner. One ninth of them are loaned out, five more than science books. How many story books and science and technology books are there?