Seven monkeys ate 13 peaches, three for each big monkey and one for each little monkey. How many big monkeys do you have?

Seven monkeys ate 13 peaches, three for each big monkey and one for each little monkey. How many big monkeys do you have?

7 * 3 = 21
(21-13) / (3-1) = 4 (pieces) Little monkey
7-4 = 3 (pieces) Big monkey

100 monkeys eat 100 peaches, one old monkey eats 4 peaches, and four little monkeys eat one peach
There are some old monkeys and little ones

x+y=100
4x+y/4=100
x=20
y=80
There are 20 old monkeys and 80 little ones

There are 48 peaches in a basket. The little monkey eats 5 peaches less than half of the basket, and the big monkey eats 5 peaches more than 13. Which monkey eats more? How many more?

48 × 12-5 = 24-5 = 19 (pieces); 48 × 13 + 5 = 16 + 5 = 21 (pieces); 21-19 = 2 (pieces). A: the big monkey eats more, 2 more

Given the absolute value of x = √ 5, √ Y & # 178; = √ 3, the absolute value of Y-X = X-Y, find the value of X, y

The absolute value of x = 5,
X = positive and negative √ 5
√y²＝√3
Y = positive and negative √ 3
The absolute value of Y-X = X-Y, indicating that x is greater than y
therefore
X = positive √ 5, y = positive and negative √ 3

When the mass ratio of metal element to oxygen is 5:2, the relative molecular weight of a + 2-valent metal oxide is 0
Explain how and why!

The oxide can be set as RO, and the molecular weight of R is X
The mass ratio of metal to oxygen in metal oxide is 5:2
Then x: 16 = 5: 2
x=80
The relative molecular mass of the oxide is 80 + 16 = 96

It is a new operation rule, such as 3 ⁃ 4 = 3 + 4 + 5 + 6 = 18, 8 ⁃ 3 = 8 + 9 + 10 = 27

Analysis,
3※4=3+4+5+6=18,
8※3=8+9+10=27,
Therefore, n * m = n + (n + 1) + (n + 2) + (n + 3) + +(n+m-1)
Understand these, the following problems will be solved
(1)5※20=5+6+7+…… +20
=[(5+20)×16]÷2
=200
(2)1*x=1+2+3+…… +x=15
That is, (1 + x) x / 2 = 15
The solution is x = 5

If the voltage applied to the fixed value resistor increases from 6V to 2V, and the current passing through changes by 0.1A correspondingly, what is the change of the corresponding electric power?
But the answer is 8 ^ 2 / 20-6 ^ 2 / 20 = 1.4W, why?
Why not use 2 * 0.1 = 0.2W?

Δ I = △ U / r = 2V / r = 0.1A r = 20 Ω Δ P = U2 × U2 / r-u1 × U1 / r = (6 + 2) × (6 + 2) / 20-6 × 6 / 20 = (64-36) / 20 = 28 / 20 = 1.4W your error occurred in: although 2V is the voltage variation, the required power variation must be: U2 × i2-u1 × I1, that is, rear voltage × rear current front voltage

​ given a + B = 2, ab = 1 / 2, find ① 1 / 2 (a-b) & # 178; ② (A & # 178; - 1) (B & # 178; - 1) ③ (a + 3) (B + 3)

1) (1 / 2) (a-b) ^ 2 = (1 / 2) [(a + b) ^ 2-4ab] = (1 / 2) (2 ^ 2-4 * 1 / 2) = (4-2) / 2 = 12) original formula = (a ^ 2) (b ^ 2) - (a ^ 2 + B ^ 2) + 1 = (AB) ^ 2 - (a + b) ^ 2 + 2Ab + 1 = 1 / 4-4 + 1 + 1 = - 7 / 43) (a + 3) (B + 3) = AB + 3 (a + b) + 9 = 1 / 2 + 3 * 2 + 9 = 31 / 2

If the voltage at both ends of a 2 ohm resistor is 110V, the current of the resistor is?

I = u / r = 110V / 2 Ω = 55A

If the abscissa of the midpoint of the line AB is equal to 2, the length of the chord AB can be obtained

Let y = kx-2 be substituted into Y & # 178; = 8x to get k ^ 2 * x ^ 2 - (4K + 8) x + 4 = 0. ① let a (x1, kx1-2), B (X2, kx2-2), according to the meaning of the problem, X1 + x2 = (4K + 8) / K ^ 2 = 2 * 2. ② x1x2 = 4 / K ^ 2 can be solved by ② to get k = - 1 or K = 2