You are multiply by -2.
term 1: 5
term 2: -10
terms 3: 20
term 4: -40
term 5: 80
term 6: -160
term 7: 320
term 8: -640
So, the 8th term is -640. Hope this helps, please mark brainliest and have an amazing day!
For the first one, it would be 5/3 and 19/3
the second one would be 40
⇒ s = a+b+c2=5+12+132 a + b + c 2 = 5 + 12 + 13 2 = 15 cm.
Area of the base = √s(s−a)(s−b)(s−c)
= √15×10×3×2 15 × 10 × 3 × 2 cm2 = 30 cm2