The area of a rectangle is 375 square meters. Its length is 10 meters more than its width. How many meters are its length and width?

The area of a rectangle is 375 square meters. Its length is 10 meters more than its width. How many meters are its length and width?

If the width is x meters, the length is (x + 10) meters
（x+10）x=375
The solution is x = 15, x + 10 = 25
A: it is 25 meters long and 15 meters wide

The area of a rectangle is s, the length is a, and the width is ()

s/a

The area of a rectangle is 84 square meters. Its length is 5 meters more than its width. The rectangle is () meters long and () meters wide

Area of rectangle = L * w = (W + 5) * w = w ^ 2 + 5 W = 84
Width ^ 2 + 5 width - 84 = 0
(W + 12) (W-7) = 0
Width = - 12m (rounding off)
Width = 7M
Length = 7 + 5 = 12m

Y = e ^ (3x-1) second derivative

y'==[e^(3x－1)]'*(3x－1)'
==3e^(3x－1)
y''==[3e^(3x－1)]'*(3x－1)
==3×3e^(3x－1)
==9e^(3x－1)

A simple calculation method of 4 / 9 times 4 + 2 / 9 times 2 plus 1 / 9 times 2

4 out of 9 times 4 + 2 out of 9 times 2 plus 1 out of 9 times 2
=1 / 9 by 16 + 1 / 9 by 4 plus 1 / 9 by 2
=1 / 9 × (16 + 4 + 2)
=1 / 9 × 22
=22 out of 9
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What's the quotient of subtracting the sum of the two numbers by the difference between two fifths and two thirds

(2 / 5 + 2 / 3) / (2 / 3-2 / 5) = 4

It is known that the solution of the equation 1 / 2 [1-x] = 1 + K and 3 / 4 [X-1] - 2 / 5 [3x + 2] about X are the same=
The sum of K / 10-3 / 2 [X-1] is 0. Try to find out how to get the value of K

First, the algebraic metric with X is used to express K, and the two equations are simplified respectively
The solution of equation (1) is as follows
X=-1-2K
The solution of equation (2) is as follows
X=（61+2K）/21
Because the sum of the solutions of the equation is 0, so
（-1-2K）+[（61+2K）/21]=0
The solution is as follows
K=1

-1+3-5+… -97 + 99 (clever calculation)

If the sum of every two adjacent terms is 2, there are 25 terms in total, then the original formula = 2x25 = 50

What is the minimum natural number with only 20 divisors? What is the sum of 20 divisors?

Let this number be p, then the standard decomposition formula is: P = P1 ^ R1 * P2 ^ R2 *... PK ^ rk (1.2... K is the subscript. ^ is the power; p1.p2.p3... PK is the prime number) then (R1 + 1) (R2 + 1)... (RK + 1) = 20 = 2 * 2 * 5 = 4 * 5 = 2 * 10. When it is the form of 2 * 2 * 5, we know: R1 = 1, R2 = 1, R3 = 4, so the minimum P = 2 ^ 4 * 3 * 5 = 240

If the value of x2 + 3x-5 is 7, then the value of 3x2 + 9x-2 is 7______ ．

The value of ∵ x2 + 3x-5 is 7, ∵ x2 + 3x = 12, substituting into 3x2 + 9x-2, the original formula = 3 (x2 + 3x) - 2 = 3 × 12-2 = 34