tolong jawab nomer 6-9

6. √0,64 = 0,8
7. √50 + √32 + √18
   = 7,071067811865475 + 5,65685424949238 + 4,242640687119285
   = 16,97056274847714
8. kurang jelas soalnya
9. 1/3 + 1/9 + 1/27 + 1/81 = 27/81 + 9/81 + 3/81 + 1/81 = 40/81