7 (x-3) = 15-x, how to solve the equation

7 (x-3) = 15-x, how to solve the equation

7（x-3)=15-x
7x-21=15-x
7x+x=15+21
8x=36
x=36÷8
x=4.5

How to solve the equation of 2 (2.8 + x) = 4?

Law of distribution
2*（2.8+x）=4
5.6+2X=4
2x=4-5.6
2x=-1.6
X=-0.8

3(82+x)=471 (x-1.8)÷4=2.5 5((X-1.8)=1.7 6(1.5+x)=13.8

3.2(x+3.8)=13.6

3.2(x+3.8)=13.6
x+3.8=4.25
x=0.45

10x-6x=24.

10x-6x=24.8
4X=24.8
X=6.2

The focus coordinates are (- 5,0) and (5,0). The sum of the distances between a point on the ellipse and two focuses is 26. The standard equation of the ellipse is obtained

The focal coordinates are (- 5,0) and (5,0) → C = 5
The sum of the distances between a point on the ellipse and two focal points is 26 → 2A = 26, and the solution is a = 13
So B = √ (a ^ 2-C ^ 2) = 12
So the standard equation of ellipse is: x ^ 2 / 169 + y ^ 2 / 144 = 1

What does x ^ 3 + 1 / x ^ 3 equal?

x^3+1/x^3=(x+1/x)(x^2-1+1/x^2)

How to compare the sizes of sin35, cos35, cot35?

Cos35 can be transformed into sin55, cot35 into tan55,
Sin35, sin55, sin55 / cos55
Because sin increases monotonically in (0,90) and cos55

Observe and analyze the following equations: x + 2 / x = 3, x + 6 / x = 5, x + 12 / x = 7; please use the laws contained in them
To find the root of the equation x + (n & # 178; + n / x-3) = 2n + 1 (n is a positive integer), what's your answer?

These equations can be changed as follows:
（1）x+1*2/x=2*1+1；
（2）x+2*3/x=2*2+1；
（3）x+3*4/x=2*3+1
So the nth equation is:
x+n(n+1)/x=2n+1
To solve this equation:
x+n(n+1)/x=2n+1
x²+n(n+1)=(2n+1)x
x²-(2n+1)x+n(n+1)=0
(x-n)(x-(n+1))=0
The solution is: x = n or x = n + 1

What's one and what's one and what's one and what's one is 17 out of 36?
Fill in different numbers

1 / 4 + 1 / 6 + 1 / 18 = 17 / 36