How to solve 5x + 3 * 0.7 = 8.5

How to solve 5x + 3 * 0.7 = 8.5

The result is: 5x + 2.1 = 8.5
The result is: 5x = 6.4
When the coefficient is 1, x = 1.28

(3x^2-2x+1)(3x^2-2x-7)+12=0
RT
Solve the equation

From (3x ^ 2-2x + 1) (3x ^ 2-2x-7) + 12 = 0, (3x ^ 2-2x + 1) (3x ^ 2-2x + 1-8) + 12 = 0, (3x ^ 2-2x + 1) ^ 2-8 (3x ^ 2-2x + 1) + 12 = 0, that is, (3x ^ 2-2x + 1-6) (3x ^ 2-2x + 1-2) = 0, that is, 3x ^ 2-2x-5 = 0 or 3x ^ 2-2x-1 = 0

If 1 / 2x + 2 = 1 / 3x, then 3x + 12 = 2x. 3x-2x + 12 = 2x-2x, that is, x + 12 = 0, x = - 12

If you write one third x, the answer is right! If you write one third x, the answer is wrong I don't know what the problem is

Let X be a system of two unknowns, and let X be a system of two unknowns
2. The solution of the system of equations is x = 2, y = 3?

The first type: y + x = 5
Y-X=1
The second: 2x + y = 7
X-Y=-1
.
There are infinitely many systems of equations

It is known that the solution of the system of linear equations of two variables about X, y is x = 2, y = 3. Write a system of linear equations of two variables satisfying the above conditions

x+y=5
3x=2y

According to the following conditions, set up equations. Urgent. To set up unknowns
(1) The absolute value of the difference between a number and 1 plus 1 equals 2
(2) The difference between 10% of X and Y is 3 times less than that of Y

1. Let a number be X
|x-1|+1=2
2、10%x-y=2y-3

Find the unknown number (x-1 / 2) △ 3 = 1 / 4

x-1/2=3/4
x=5/4

Can two unknowns of quadratic equation of two variables be the same? If not, what is the inverse problem? {3x + 2Y = 5 {y = 2x-1

Substituting y = 2x-1 into the above formula, i.e
3x+2(2x-1)=5
3x+4x-2=5
7x=7
x=1
y=2x-1
=2-1
=1
The value of two unknowns can be the same

The square of 9x plus 6x plus 1 equals 4

9x²+6x+1=4
9x²+6x-3=0
3x²+2x-1=0
(3x-1)(x+1)=0
X = 1 / 3 or x = - 1

11x+42-2x=100-9x-22

11x+42-2x=100-9x-22
11x-2x+9x=100-22-42
18x=36
x=2