Month Value
1 16000
3 31000
4 42000
7 110000
8 180000
9 225000

Over a 9-month period an account increased in value as shown in the table, with values in dollars. Find a quadratic curve of best fit for this data.

A) y = 14700 + 6700x - 8800x2
B) y = 18900 + 12100x - 500x2
C) y = 22300 + 28200x + 1400x2
D) y = 29600 - 13300x + 3880x2

step by step resolutions

1) n+n+1+n+2=51

3n+3=51

3n=48

n=16

the three numbers are 16, 17 and 18.

2) x+15=4x

3x=15

x=5

radha is now 5 years old

3) the two digits are x and y.

y=3x

(10x+y)+(10y+x)=88

y=3x

11x+11y=88

y=3x

x+y=8

x+3x=8

x=2

the original number can be either 28 or 82.

4) n+(n+2)+(n+4)=48

3n+6=48

3n=42

n=14

the numbers are 14, 16 and 18.

5) y=x+3

10y+x+10x+y=143

y=x+3

11x+11y=143

y=x+3

x+y=13

x+x+3=13

2x=10

x=5

the original number can be 57 or 75.

hope this !

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