From the numbers in brackets of the following questions, find out the solution of the previous equation: 3 / 5x-8 = 1 (x = 15, x = - 5); 3 (x + 1) = 12 (x = 3, x = 5),

From the numbers in brackets of the following questions, find out the solution of the previous equation: 3 / 5x-8 = 1 (x = 15, x = - 5); 3 (x + 1) = 12 (x = 3, x = 5),

3 / 5x-8 = 1. To move the term from - 8 on the left side of the equal sign to 8 on the right side of the equal sign
3/5x＝1+8,
3/5x＝9,
Multiply both sides of the equation by 5 to get:
3x=5X9,
3x=45,
x=15.
3 (x + 1) = 12, divide both sides of the equation by 3 at the same time to get:
x+1=4,
x=4-1,
x=3.

Given that 1x − 1y = 3, then the value of the algebraic expression 2x − 14xy − 2yx − 2XY − y is______ ．

Solution 1: ∵ 1x-1y = - x − YXY = 3, that is, X-Y = - 3xy, then the original formula = 2 (x − y) − 14xy (x − y) − 2XY = - 20XY − 5xy = 4. Solution 2: divide the numerator and denominator of the original formula by XY at the same time, 2x − 14xy − 2yx − 2XY − y = 21y − 14 − 21x1y − 2 − 1x = 2 × (− 3) − 14 − 3 − 2 = 4, so the answer is: 4

What is the maximum value of 2x + y when x + 2Y is less than or equal to 3 and X is greater than or equal to 0

It is known that x + 2Y is less than or equal to 3, X is greater than 0, X is less than or equal to 3-2y is greater than 0, y is less than three-thirds
2X + y = 2 & lt; X + 2y-3y is less than or equal to 2 times 3-3 times 3 / 2 equals 3 / 2
The answer is three in two