How to solve this equation

How to solve this equation

2 / 5 ／ 2 / 3 ／ x = 7 / 15
3/5=7/15x
x=3/5×15/7
x=9/7
9 out of 7

(sin22 degree + cos45 Degree * sin23 degree) / cos22 degree - sin45 Degree * sin23 degree, simplification

(sin22 degrees + cos45 degrees * sin23 degrees) / cos22 degrees - sin45 degrees * sin23 degrees
=(sin22 degrees + cos (22 + 23) degrees * sin23 degrees) / cos22 degrees - sin (22 + 23) degrees * sin23 degrees
=(sin22 degree + cos22cos23sin23-sin22sin23 ^ 2) / cos22 degree - sin22cos23sin23-cos22sin23 ^ 2
=[sin22(1-sin23^2)+cos22cos23sin23]/[cos22(1-sin23^2)-sin22cos23sin23]
=(sin22cos23^2+cos22cos23sin23)/(cos22cos23^2-sin22sin23cos23)
=(sin22cos23+cos22sin23)/(cos22cos23-sin22sin23)
=sin(22+23)/cos(22+23)
=tg45
=1

Four times of 5.2 is more than one fourth of what

Let this number be X
5.2*4-1/4x=2.8
1/4x=20.8-2.8
1/4x=18
x=72

Li Lin read 5 / 9 of a book in 7 days?

The average number of people reading this book every day: 5 / 9 / 7 = 5 / 63

Given the point m (2a-1,3a), when - 1 ＜ a ＜ 0, what quadrant is the point m in

－1

How many milliseconds is one minute?

One millisecond is equal to one thousandth of a second (10-3 seconds). 0.000 000 001 millisecond = 1 picosecond. 0.000 001 millisecond = 1 nanosecond. 0.001 millisecond = 1 microsecond. 1000 millisecond = 1 second

[x ^ 2 / | m | - 1] + [y ^ 2 / m-2] = 1 represents the ellipse with focus on the y-axis, then the value range of M

Because [x ^ 2 / | m | - 1] + [y ^ 2 / m-2] = 1 represents the ellipse with the focus on the y-axis
00 and | m | - 1

The known function f (x) = 2cos ^ 2x + 2sinxcosx + 1

f(x)=2cos^2x+2sinxcosx+1
=cos2x+1+sin2x+1
=√2sin(2x+π/4)+2

When k takes what value, the intersection of the line y = - 2x-2k and the line x + 2Y + K + 1 = 0 is in the fourth quadrant?

Y = − 2x − 2kx + 2Y + K + 1 = 0, the solution is x = − K + 13y = − 23, ∵ the intersection is in the fourth quadrant, ∵ x > 0, ∵ K + 13 > 0, the solution is k < 13

Given f (2x) = 3x & # 178; + 1, find the analytic formula of F (x)

x² = (2x)²/4
So, it's OK to replace 2x with X
f(x)=3*x²/4+1