Given a, B, C, D ∈ R, prove AC + BD ≤ √ [(A2 + B2) (C2 + D2)]

First of all, if AC + BD

RELATED INFORMATIONS

1. In Excel, if A1 = C1, then B1 = D1; if A1 = C2, then B1 = D2; if A1 = C3, then B1 = D3?
2. In Excel, in column a, A1 = B1 + C1, A2 = B2 + C2 + D3, A3 = B3 + C3 + D3 + F3. How to express it by formula
3. How to realize the circulation of A1 = B1 A2 = C1 A3 = D1 A4 = E1 A5 = B2 A6 = C2 in excel?
4. When A1 ≠ A2 and C1 = C2, B1 = A2 or B2 = A1 (2) when A1 ≠ A2 and C1 = C2, D1 = E2 or D2 = E1 There are many repeated values in column a, many repeated values in column C, many repeated values in column e, and null values in columns B and D
5. The four factors of the three levels of orthogonal experiment design are: A1, A2, A3, A4, B1, B2, B3, B4, C1, C2, C3, C4
6. How many terms of (a1 + A2 + a3 + A4) (B1 + B2 + B3) (C1 + C2 + C3 + C4 + C5) product? Why?
7. How many items in the product (a1 + A2 + a3) (B1 + B2 + B3) (C1 + C2 + C3 + C4 + C5) after expansion The counting principle of classified addition and the counting principle of distributed multiplication in senior two
8. In parallelogram ABCD, de bisects AB vertically, the perpendicular foot is point E, the perimeter of parallelogram ABCD is 36cm, and the perimeter of triangle abd is 10cm less than that of parallelogram ABCD. The length of AB and BC can be calculated Urgent need
9. ▱ the circumference of ABCD is 36 & nbsp; cm, ab = 57bc, then the length of the longer side is () A. 15cmB. 7.5cmC. 21cmD. 10.5cm
10. As shown in the figure, in the parallelogram ABCD, point m is on the extension line of Da, point n is on the extension line of DC, and Mn ‖ AC and Mn intersect AB and BC at points P and Q respectively ① Try to explore the size relationship between MQ and NP ② If Mn intersects the extension lines of AB and CB at points P and Q respectively, does the size relationship between MQ and NP still hold? Illustration:
11. Four unequal integers a, B, C, D, if their product ABCD = 25, then a + B + C + D=
12. Four different integers a, B, C, D, their product ABCD = 25, then what is a + B + C + D equal to?
13. If the integers a, B, C and D satisfy ABCD = 25 and a > b > C > D, then | a + B | + | C + D | equals () A. OB. 10C. 2D. 12
14. If ABCD is a rational number, the absolute value of A-B is ≤ 9, the absolute value of C-D is ≤ 16, and the absolute value of a -- B-C + D is equal to 25, then the absolute value of B-A is subtracted The absolute value of d-c is equal to?
15. Given that ABCD is a rational number, the absolute value of a minus B is less than or equal to 9, the absolute value of C minus D is less than or equal to 16, and the absolute value of a minus B minus C plus D is equal to 25, find the absolute value of B minus a minus D minus C
16. Given that ABCD is a rational number, the absolute value of (a-b) is less than or equal to 9, the absolute value of (C-D) is less than or equal to 16, and the absolute value of (a-b - + D) is 25, find the absolute value of (- a)
17. 57 79 87 49 which is prime
18. 91 =? (prime)
19. Prime a × prime B = 91, then, prime a + prime B =?
20. What are the prime numbers of 91