It is known that Tan α = - 2, Tan β = 1 / 3, where 0 < α < π, 0 < β < π. (1) find the value of Tan (α - β) (2) Find the value of α + β

It is known that Tan α = - 2, Tan β = 1 / 3, where 0 < α < π, 0 < β < π. (1) find the value of Tan (α - β) (2) Find the value of α + β

Use a, B instead,
(1) tan(a-b)
=(tana-tanb)/(1+tanatanb)
=(-2-1/3)/[1-2*(1/3)]
=(-7/3)/(1/3)
=-7
(2)tana

L passes through PQ, and the abscissa of point P is 3 larger than that of Q, and the ordinate of P is 2 smaller than that of Q. the distance from the intersection point of line L and Y axis to X axis is 2. Find the square of line L

According to the meaning of the title
L is a line with a negative slope k, k = - 2 / 3
Then l = - 2x / 3 + 2

How many seconds is 450 days

450 days = 450 * 24 * 3600 = 38880000 (seconds)

Find the linear equation which is parallel to the line 2x + 3Y + 5 = 0 and the sum of intercept on two coordinate axes is 5 / 6

Let the intercept formula of straight line X / A + Y / b = 1, where a + B = 5 / 6, then use the same K of two straight lines to find the value of a and B, that is, the equation of straight line

Simple calculation method: 1.1.1 + 2.2 + 3.3 + 4.4 + 5.5 + 6.6 + 7.7 + 8.8 + 9.9 2.14.5 + 6.65 * 39.9 + 25.4 + 2.35 * 39.9
There are two questions

1. The original formula = (1 + 2 + -- + 9) + (0.1 + 0.2 + -- + 0.9) = (1 + 2 + -- + 9) * 1.1 = 49.5
2. The original formula = 39.9 * (1 + 6.65 + 2.35) = 39.9 * 10 = 399

The line L: 3x + 4Y + 24 = 0 intersects with the x-axis and y-axis at two points a and B respectively, and O is the coordinate origin. The circumscribed circle equation of the triangle AOB is solved

A:y=0,x=-8
B:x=0,y=-6
|AB|=√（6^2+8^2)=10
ABO is a right triangle, the center of circumscribed circle is on the midpoint (- 4, - 3) of hypotenuse AB, and the radius is half of hypotenuse 5
So the equation is: (x + 4) ^ 2 + (y + 3) ^ 2 = 25

 y we know that f (x) = 3x ^ 2-2x, the sum of the first n terms of the sequence an is Sn, and the point (n, Sn) is in the function y = f (x)
If y is known that f (x) = 3x ^ 2-2x, the sum of the first n terms of the sequence an is Sn, and the points (n, Sn) are all on the function y = f (x), find an BN = 1 / an * a (n + 1) to make the first n terms of BN and TN, and find TN

X = n f (x) = SN is substituted into the functional equation: when Sn = 3N & # 178; - 2nn = 1, S1 = A1 = 3-2 = 1n ≥ 2, Sn = 3N & # 178; - 2n s (n-1) = 3 (n-1) & # 178; - 2 (n-1) an = SN-S (n-1) = 3N & # 178; - 2n-3 (n-1) & # 178; + 2 (n-1) = 6n-5n = 1, A1 = 6-5 = 1, which also satisfies the general term formula of sequence {an} is an =

The total edge length of a cube is 36 cm, and its surface area is______ ．

The edge length is: 36 △ 12 = 3 (CM), the surface area is: 3 × 3 × 6 = 54 (square cm); answer: its surface area is 54 square cm. So the answer is: 54 square cm

Given that the equation / X / = ax + 1 has a negative root but no positive root, we can find the value range of A

x-1

-How much smaller is the sum of 4, 5 and - 7 than the sum of their absolute values?

（4+7）×2=22