3x+2.5（70-x ）=189

3x+2.5（70-x ）=189

3x+2.5（70-x ）=189
3x+2.5×70-2.5x=189;
0.5x=189-175;
0.5x=14;
x=28;
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How to solve the equation of 18 * 5 / 2x + 5 / 3x * 8 = 3000

18 * 5 / 2x + 5 / 3x * 8 = 3000
36x / 5 + 24x / 5 = 3000
12X=3000
X=3000/12
X=250

Two adjacent natural numbers must be coprime numbers______ (judge right or wrong)

According to the meaning of Coprime number, two numbers with only 1 common factor are called coprime numbers. Because 0 and 1 have no common factor, 0 and 1 are not coprime numbers. Therefore, two adjacent natural numbers must be coprime numbers. This statement is wrong. So the answer is wrong

Is 0 a natural number? Is 0 an integer?

0 is both a natural number and an integer. Integers include positive integers, 0 and negative integers

1 first row 2, 3 second row 4, 5, 6 third row 7, 8, 9, 10 fourth row What is the 56th number in row 63

The nth row has n numbers, and the last number is 1 + 2 + 3 + 4 + +N=N（N+1）/2
Substituting n = 63, the number of 63 rows is 63 × 64 / 2 = 2016
Then the 56th number is 2016 - (63-56) = 2009

To prove that the cubic sum of three continuous natural numbers can be divisible by 9

A ^ 3 + (a + 1) ^ 3 + (A-1) ^ 3 = a ^ 3 + A ^ 3 + 3A ^ 2 + 3A + 1 + A ^ 3-3a ^ 2 + 3a-1 = 3A ^ 3 + 6A = 3A (a ^ 2 + 2) 1. A = 3N, then the original formula can be divisible by 9, 2. A = 3N + 1, 3A can be divisible by 3, a ^ 2 + 2 = 9N ^ 2 + 6N + 3 = 3 (3N ^ 2 + 2n + 1) can also be divisible by 3, 3. A = 3N + 2, a ^ 2 + 2 = 9N ^ 2 + 12n + 6 = 3 (3N ^ 2 + 6N + 2) can also be divisible by 3

A = radical 5 + 2 b = radical 5-2, then the value of a square + b square + 7 under the radical

ab=5-4=1
a+b=2√5
Square on both sides
a²+2ab+b²=20
So a & # 178; + B & # 178; = 20-2ab = 18
So the original formula = √ (18 + 7) = 5

1.what letter should next?Z X U Q L

F

Find the plane equation perpendicular to the plane x-4y + 5z-1 = 0 and passing through the origin and point (- 2.7.3)

Because the plane passes through the origin, let the plane equation: ax + by + CZ = 0
The two planes are perpendicular, so the normal vectors of the two planes are perpendicular, as follows: (a, B, c) * (1, - 4,5) = 0 -- > a-4b + 5C = 0
And because - 2A + 7b + 3C = 0
A = 47c, B = 13C
So the plane equation can be reduced to: 47x + 13y + Z = 0

If n is an integer and N ≤ x ＜ n + 1, then n is the integral part of X +1 / 1980) and 1 / (1 / 2009 + 1 / 2009 + +1 / 2009) can be determined as x = 1 / (1 / 1980 + 1 / 1981 + 1 / 1982 + +The integral part of (1 / 2008 + 1 / 2009) is ()

Answer 66
The result of calculating the first formula is
1980 / 30 = 66 the integral part is 66
The second formula
2009 / 30 = 66 and 29 / 30 the integral part is 66
The required formula can prove that the value is between the first two formulas
So the whole number is 66