Calculate the inverse matrix of 2 - 31 | 4 - 52 | 5 - 73 in three rows and three columns?

Calculate the inverse matrix of 2 - 31 | 4 - 52 | 5 - 73 in three rows and three columns?

Solution: according to the formula A-1 = 1 / | a | a * | a | = 1 ≠ 0 (a reversible)
Calculate a * a11 = - 1, A12 = 2, A13 = - 3
A21=-2 A22=1 A23=1
A31=-1 A32=0 A33=2
Finally, A-1 is obtained

Let a and B be matrices of third order and | a | = 3 | B | = 2 | A-1 + B | = 2 find | a + B-1 |, where A-1 is the inverse matrix

From the matrix property | ab | = | a | B |, we know that | a (A-1 + b) | = | e + ab | = 3 * 2 = 6,
Then | a + B-1 | = | (a + B-1) B | / | B | = | e + ab | / 2 = 6 / 2 = 3

Point P (1,2) and circle x ^ + y ^ = 9, make two mutually perpendicular chords through P, intersect circle a and B, and find the trajectory equation of point m in ab
It's better to have a picture. If not, the explanation should be clear

AB midpoint m (x, y)
xA+xB=2x,yA+yB=2y
(xA+xB)^2=(2x)^2
(xA)^2+(xB)^2+2xA*xB=4x^2.(1)
(yA)^2+(yB)^2+2yA*yB=4y^2.(2)
(xA)^2+(yA)^2=9.(3)
(xB)^2+(yB)^2=9.(4)
PA⊥PB
k(PA)*k(PB)=-1
[(yA-2)/(xA-1)]*[(yB-2)/(xB-1)]=-1
2xA*xB+2yA*yB=2[(xA+xB)+2(yA+yB)-5]=4x+8y-10.(5)
(1)+(2)-(3)-(4)-(5):
4x^2+4y^2-4x-8y-8=0
Trajectory equation circle of point m in AB:
(x-0.5)^2+(y-1)^2=3.25

9 divided by 4 equals 4 divided by 9 equals () just fill in one fraction

9 divided by 4 equals 4 divided by 9 equals (9 / 4) just fill in one fraction

The line L passes through a point P (- A / 2, a / 3) on the line L1: 3x + 4Y + 1 = 0, and the inclination angle α is half of the inclination angle of the line L1. The equation of the line L is obtained

Tan tilt angle L1 = (- 3 / 4) tilt angle α = 1 / 2 tilt angle l1tan2a = - 3 / 4 = (2tana) / (1-tana ^ 2) 8tana = 3tana ^ 2-33tan ^ 2-8tana-3 = 0tana = - 1 / 3 Tana = 3Y = - 1 / 3x + BA / 3 = a / 6 + BB = A / 6y = - 1 / 3x + A / 6y = 3x + BA / 3 = - 3A / 2 + BB = 11a / 6y = 3x + 11a / 6

5-8 (4 / X-2 / 5) = 3x to solve the equation

5-8 (x / 4-5 / 2) = 3x
5-2x+20=3x
3x+2x=5+20
5x=25
x=25÷5
x=5

If P: exists x ∈ R, AX2 + 2x + 1 > 0 is true proposition, then what is the value range of real number a?
If AX2 + 2x + 1 > 0 is true for any p: X ∈ R, what is the range of real number a?

When a > 0, △ 1
Therefore, when a > 1, the meaning of the question is satisfied

How to divide 395 by 283 * 254 by 39.5 * 2.83 by 2.54

395÷283×254÷39.5×2.83÷2.54
= (395÷39.5) × (254÷2.54) ×( 2.83÷283)
= 10 × 100 × 0.01
= 10

The equation of the line passing through point P (1,2) and perpendicular to the line x-2y + 3 = 0 is?

Given that the slope of the line is 1 / 2, the slope of the line is - 2 (because they are vertical)
So let y = - 2x + B be substituted into P (1,2) and B = 4
So the line y = - 2x + 4

How to write English words from 31 to 99

31thirty-one
32thirty-two
33thirty-three
34thirty-four
35thirty-five
36thirty-six
37thirty-seven
38thirty-eight
39thirty-nine
40forty
41forty-one
42forty-two
43forty-three
44forty-four
45forty-five
46forty-six
47forty-seven
48forty-eight
49forty-nine
50fifty
51fifty-one
52fifty-two
53fifty-three
54fifty-four
55fifty-five
56fifty-six
57fifty-seven
58fifty-eight
59fifty-nine
60sixty
61sixty-one
62sixty-two
63sixty-three
64sixty-four
65sixty-five
66sixty-six
67sixty-seven
68sixty-eight
69sixty-nine
70seventy
71seventy-one
72seventy-two
73seventy-three
74seventy-four
75seventy-five
76seventy-six
77seventy-seven
78seventy-eight
79seventy-nine
80eighty
81eighty-one
82eighty-two
83eighty-three
84eighty-four
85eighty-five
86eighty-six
87eighty-seven
88eighty-eight
89eighty-nine
90ninety
91ninety-one
92ninety-two
93ninety-three
94ninety-four
95ninety-five
96ninety-six
97ninety-seven
98ninety-eight
99ninety-nine