3(x-7)-5(4-x)=15

3(x-7)-5(4-x)=15

3(x-7)-5(4-x)=15
3x-21-20+5x=15
3x+5x=15+21+20
8x=56
x=7

Test whether the following numbers are solutions of the equation 5x-2 = 7 + 2x, and write the test process (1) x = 2 (2) x = 3

5 * 2-2 = 8,7 + 2 * 2 = 11, so x = 2 is not the solution of the equation,
5 * 3-2 = 13,7 + 2 * 3 = 13, so x = 3 is the solution of the equation

3 (x + 1) = 2x-1. (x = 0, x = - 4)

When x = 0, left = 3 * 1 = 3, right = - 1, so left is not equal to right, so x = 0 is not the solution of the equation
When x = - 4, left = 3 * (- 3) = - 9, right = - 8-1 = - 9, so left equals right, so x = - 4 is the solution of the equation

English translation
Can you help me get that dress down?
What color do you like?
Translation!

can you help me putting that clothes down?
what colour's clothes do you like

How many centimeters is an inch

Because one meter is 100 cm
One meter is three feet, or 30 inches,
So one inch is 3.33333cm

Find Lim {B (B / a) n power / [1 + (B / a) n power]}, and 0

Multiply (A / b) ^ n, a / B at the same time

English translation
SOS

My mather doesn't like traveling by car.Because she sick of car.

It is proved that the square difference of two consecutive odd numbers is a multiple of 8
Let two consecutive odd numbers be 2K + 1 and 2k-3 (k is a positive integer)
Wrong number on it, 2K + 1 and 2K + 3

Let two consecutive odd numbers be 2K + 1 and 2K + 3 (k is a positive integer)
Square difference = (2k + 3) &# 178; - (2k + 1) &# 178;
=4k²+9+12k-4k²-4k-1
=8+8k;
So it must be a multiple of eight
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Ask high number master: function f (x), the following f (x) derivative is not continuous at x = 0, right?
When f (x) = x not = 0 (x-1 / X of E)
When x = 0 (1)
When f (x) = x not = 0 (LN (1 + x) / x)
When x = 0 (1)

1、f(x)=(e^x-1)/x,x≠0
lim(x→0)(e^x-1)/x=lim(x→0)e^x=1=f(0)
So f (x) is continuous at x = 0
2、lim(x→0)ln(1+x)/x=lim(x→0）ln(1+x)^(1/x)=lne=1=f(0)
So f (x) is continuous when x = 0

The price of a commodity is p% higher than the cost. When the commodity is sold at a lower price, in order not to lose money, the price reduction should not exceed d%. If P is used to express D, then d = 0___ ．

Let the cost price be 1, then (1 + P%) (1-D%) = 1.1-d% = 11 + P%, d% = 1-100100 + PD% = P100 + P, ∧ d = 100p100 + P