In the first quarter of a factory, the electricity cost was a yuan, and the water cost was 14 yuan more than twice the electricity cost. In the second quarter, the electricity cost was saved by 15%, and the water cost was 38% more Compared with the first quarter, the second quarter water and electricity cost is overspending or saving

First quarter water and electricity cost a + 2A + 14 = 3A + 14
Water and electricity charges in the second quarter a * (1-15%) + (2a + 14) * (1 + 38%) = 3.61a + 14 * 1.38 = (3a + 14) + 0.61a + 14 * 0.38
In the second quarter, the water and electricity cost was 0.61a + 14 * 0.38 more than that in the first quarter
So it's overspending

The electricity charge of a factory in the first quarter is a yuan, and the water charge is 40 yuan more than twice the electricity charge, saving 25% of the electricity charge in the second quarter
However, the water cost was 38% more. Q: compared with the first quarter, the water and electricity cost of the factory in the second quarter was overspent or saved? How many yuan was overspent or saved

A + 2A + 40 = 3A + 40 yuan in the first quarter
In the second quarter, a total of (1-25%) a + (1 + 38%) (2a + 40) = 0.75a + 2.76a + 55.2 = 3.51a + 55.2 yuan
So I overspent
Overspending 3.51a + 55.2 - (3a + 40) = 0.51a + 15.2 yuan

Application problem, to comprehensive calculation, crab crab!
3. The students send little red flags to the children in the kindergarten. The little red flags made by class five (1) and class five (2) are distributed to three classes in the kindergarten, with an average of 180 flags for each class. How many red flags have class five (1) and class five (2) made for each class?
4. There are 34 elderly people in the nursing home, and the average age of the elderly is 82.5 years old. Among them, there are 21 grannies, with an average age of 85 years old; there are 13 grandfathers, with an average age of how old? (use the "rounding" method to keep the number to one decimal place)

3、
180 times 3 divided by 2 = 270
A: Class 5 (1) and class 5 (2) made 270 red flags on average
4、
(34 times 82.5-21 times 85) divided by 13
=(2805-1785) divided by 13
=1020 divided by 13
=78.5
A: the average age of my grandfather is 78.5 years old

If the work efficiency is increased by 15 after 4 days, half of the parts will be finished. It will take a long time______ Day

It takes X days to complete half of this batch of parts, ∵ 18 days to complete its 13. The original planned work efficiency is 154, ∵ 154 × 4 + 154 × (1 + 15) (x-4) = 12. The solution is x = 2316, so the answer is 2316

It is known that the period of a sinusoidal voltage is 10 ms and the initial phase is 0.628 rad. When t = 1.5 ms, its instantaneous value is 0.012 v

If the voltage amplitude is V, then V (T) = VSiN [((2 π / T) * t) + 0.628] = VSiN (200 π T + 0.628) when t = 0.0015, v = 0.012 is brought into the above formula: 0.012 = VSiN (200 π * 0.0015 + 0.628) = VSiN (0.3 π + 0.2 π) = VSiN (π / 2), then v = 0.012

When a class goes on a spring outing, it's just right for 12 people to take a car. When they come back, it's just right for 8 people to take a car. How many people are there in this class at least?

8 = 2 × 2 × 2, 12 = 2 × 2 × 3, the least common multiple of 8 and 12 is 2 × 2 × 2 × 3 = 24, that is, there are at least 24 students in this class

Given that a is a square matrix of order n and satisfies the relation a ^ 2 + 3A + 4E = 0, then (a + e) ^ - 1=

Obviously, it can be obtained from a ^ 2 + 3A + 4E = 0
(A+E)(A+2E)= -2E,
That is, (a + e) (- A / 2 - E) = e,
So we can see from the definition of inverse matrix,
(A+E)^-1= -A/2 -E

Why the plural

As we all know, negative numbers have no real square root, so the quadratic equation with discriminant less than 0 has no solution. To solve this problem, the mathematician Cardano first introduced the complex number. He expressed the pure imaginary number as negative root. In fact, he also felt very contradictory. On the one hand, he felt that the imaginary number was illusory and constructed, "nothing", but

The fifth grade organized spring outing. 98 teachers and students went boating. They rented 20 boats, 6 for each big boat and 4 for each small boat
How many boats are there?

There are x large boats and 20-x small boats
6X+4(20-X)=98
6X+80-4X=98
2X=18
X=9
There are 9 big boats and 11 small boats

When x tends to π / 6, find LIM (2Sin ^ 2x + sinx-1) / (2Sin ^ 2x-3sinx + 1) limit
Mainly the simplification of trigonometric function

When pi / 6 is substituted in, it is of type 0 / 0. You can use the law to find the upper and lower derivatives, so it becomes
lim（2*2*sinx*cosx+cosx）/(2*2*sinx*cosx-3cosx)
And then divide it up and down, and get it
lim(4sinx+1)/(4sinx-3)
And then I put pi / 6 in and I get
-3