Answer:
an = 1/2 (n) (n+1)
Step-by-step explanation:
1,3,6,10,.........
3-1=2
6-3=3
Each term is different so there is no common difference. It is not an arithmetic sequence
3/1=3
6/3 =2
Each term is different so there is no common ratio. It is not a geometric sequence
1 3 6 10
+2 +3 +4
a1 = 1
a2 = 3
a3 = 6 = 2*3
a4 = 10 = 2*5
I need help with this too i dont know the process
Side side side
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11x(x+2) should be the answer
"Supplementary" angles add up to 180°.
Opposite angles are supplementary, so . . .
(12x - 4) + (19x - 2) = 180°
Clear the parentheses: 12x - 4 + 19x - 2 = 180°
Add up all the x's on the left side: 31x - 4 - 2 = 180°
Add up the plain old numbers on the left side: 31x - 6 = 180°
Add 6 to each side: 31x = 186°
Divide each side by 31 : <em>x = 6°</em>
Well ! Now that you know that x = 6° . . .
Angle EPC is (12x - 4)°
That's (12·6 - 4)°
Which is (72 - 4)°
Which is <em>68°</em>
