What is the 20th term of the arithmetic sequence 8,5,2

（-3）*20+8=-52

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1. It is known that: as shown in the figure, in RT △ ABC, ∠ C = 90 ° and ∠ a = 30 ° take AB and AC as edges respectively, and make equilateral △ Abe and equilateral △ ACD on the outside of △ ABC, de and ab intersect with F, proving: EF = FD
2. As shown in the figure, △ Abe and △ ACD are respectively formed by △ ABC folding along AB and AC sides. If ∠ BAC = 150 °, then ∠ DAB =, ∠ DAE= Why
3. Taking the two right sides AB and BC of the right triangle ABC as one side, make the equilateral triangle △ Abe and equilateral △ BCF outward respectively, connecting EF and EC. Try to explain: (1) EF = EC; (2) EB ⊥ CF
4. Taking the two right sides AB and BC of the right triangle ABC as one side, make the equilateral triangle △ Abe and equilateral △ BCF outward respectively, connecting EF and EC. Try to explain: (1) EF = EC; (2) EB ⊥ CF
5. Known: as shown in the figure, take two right angle sides AB and BC of RT △ ABC as sides to make equilateral △ Abe and equilateral △ BCF, connect EF and EC, please explain EF = EC
6. In the triangle ABC, CD is high, e is the midpoint of CD, the extension line of AE intersects CB at point F, AE = CE and AF is vertical to CB. If EF = 1, then AE
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9. As shown in the figure, the side length of equilateral triangle ABC is 6, ad is the middle line on the side of BC, M is the moving point on ad, e is the point on AC, if AE = 2, then the minimum value of EM + cm is?
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13. Arithmetic sequence 8, 5, 2 Item 20 of the report is______ ．
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15. Insert three numbers between 20 and 70, so that these five numbers become arithmetic sequence. What are the three numbers inserted?
16. Will 1, 2 If the nine numbers are divided into three groups averagely, the probability that the three numbers in each group can form an arithmetic sequence is () A. 156B. 170C. 1336D. 1420
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