A kind of fast growing water plant, the number of which increases twice every day. Put one plant in a pond and the pond will be full in 30 days. If it is required to be full in 26 days, put () plants in the pond

A kind of fast growing water plant, the number of which increases twice every day. Put one plant in a pond and the pond will be full in 30 days. If it is required to be full in 26 days, put () plants in the pond

Twice as much every day, that is, the next day is three times as much as the first day
The first day, the second day, the third day, the fourth day
1 39 27 deduces the formula: the (x-1) power X of 3 is the number of days
The (30-1) power of 3 and the 29th power of 3 are the size of the pond
The (30-1) power of 3 / the (26-1) power of 3 the fourth power of 3 is equal to 81
To put 81 trees, 26 days to grow a full pond
Put in one of these plants and the pond will be full in 30 days;
Put in three of these plants and the pond will be full in 29 days;
Put in nine of these plants, and the pond will be full in 28 days;
Put in 27 of these plants, and the pond will be full in 27 days;
Put in 81 of these plants and the pond will be full in 26 days

1. There are two piles of coal a and B, of which 94 tons are in pile a and 138 tons are in pile B. if nine tons are carried away in two piles every day, how many days later will b be three times as much as a?
2. There are 40 oil barrels, each of which is 5kg in big barrel and 2kg in small barrel. All the oil in big barrel is 32kg more than that in small barrel. How many oil barrels are there?

1. Suppose that after X days, B is three times as much as a
3(94-9x)=138-9x
282-27x=138-9x
144=18x
x=8
A: eight days later, B is three times as much as a
2. If there are x large buckets, then there are (40-x) small buckets
5x-32=2(40-x)
5x-32=80-2x
7x=112
x=16
So 40-x = 40-16 = 24
A: there are 16 big barrels and 24 small barrels
Should be right, I hope you can rate him as the best answer, I also have to, in order to win wealth value! Please

(to formulate)
There were 88 cars in the parking lot, but now there are 4 more left than left. How many left?

88-4=84
84/2=42
42 + 4 = 46, so simple

A third grade math problem? Requires formula calculation!
The birthdays of Xiao Ming and his father are both Wednesdays in April, but Xiao Ming's date is early. The total date of the two is 38. What are the birthdays of Xiao Ming and his father in April?

Equation: Xiaoming: x + X + 8 = 38
2X=30
X=15
Father: 38-15 = 23
Count:
Xiao Ming: (38-8) / 2 = 15
Father: 38-15 = 23
Give me a good one,

The common factor of polynomial 9x ^ 2-12x + 4 and 9x ^ 2-4 is___ .
2.9^3+2×9^2+9+10^2
3. If a ^ 2-4a + 9b ^ 2 + 6B + 5 = 0, find the value of ab
You don't have to do the third one

(1)4x(a+b)-3x²(a+b);
(2)a(x-2y)-b(2y-x)-c(x-2y);
(3)15a²(x-y)-5a(y-x);
(4)(3x+y)(3x-y)-(x+3y)(y-3x);

(1)4x(a+b)-3x²(a+b); =x(a+b)(4-3x)(2)a(x-2y)-b(2y-x)-c(x-2y); =a(x-2y)+b(x-2y)-c(x-2y); =(a+b-c)(x-2y)(3)15a²(x-y)-5a(y-x); =15a²(x-y)+5a(x-y)=5a(x-y)(3a+1)(4)(3x+y)(3x-y)-(x+3y)(y-3x);...

(a+b)²-4（a+b）+3=?
(x+y)²+4（x+y+1）=?

(a+b)²-4(a+b)+3
=[(a+b)-1][(a+b)-3]
=(a+b-1)(a+b-3)
(x+y)²+4(x+y+1)
=(x+y)²+4(x+y)+4
=[(x+y)+2]²
=(x+y+2)²

x²-2bx-ax-2ab

x²-2bx-ax-2ab
=x²-(2b+a)x-2ab
=(x-b-a/2)²-(2b+a)²/4-2ab

The square of 2A (the square of X + 1) - the square of 2aX
The square of 20a, the square of bx-45bxy
Square of 49 (a-b) - square of 16 (B-A)
Square of (a-b) (3a + b) + square of (a + 3b) (B-A)
Square of 4-12 (X-Y) + 9 (X-Y)
X squared (Y squared-1) + 2x (Y squared-1) + (Y squared-1)
Square of 9 (a-b) + 12 (a-b) + 4 (a + b)

Mathematical factorization questions need detailed process and split answers
X Cubic - 3x & # 178; + 4

Original form
=x³-2x²+4-x²
=x²(x-2)-(x-2)(x+2)
=(x-2)(x²-x-2)
=(x-2)(x-2)(x+1)
=(x-2)²(x+1)