The square of one plus the square of two plus the square of three Plus the square of n equals?
1^2+2^2+3^2+…… +n^2=n(n+1)(2n+1)/6
RELATED INFORMATIONS
- 1. It is known that when △ ABC, ∠ ACB = 90 °, CE ⊥ AB is on e, D is a point on AB, and ad = AC, AF square ∠ CAE intersects CE on F, FD ∥ BC is proved
- 2. In the triangle ABC, a, B and C are the diagonals of side a, B and C respectively, and A-B = 4, a + C = 2B. The maximum angle is 120 degrees?
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- 9. Magnesium nitride electronic type
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- 13. As shown in the figure, make the bisector ad of angle ∠ a of △ ABC, if AC + CD = AB, AC = BC, find the area of triangle ABC Under the condition of (1), extend ad to e, make ∠ DCE = CAD, prove that ad = 2ce
- 14. In the known △ ABC, a = 45 °, C = 30 ° and C = 10cm, the triangle is solved
- 15. The definition and range of y = 3arcsin (x-1)
- 16. If a > 0, B
- 17. The result of his calculation is different from the correct answer ()
- 18. (5.87+1514+2.13+914)×(234−1.75)+(1÷27−3.5)×3.99.
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