How do you do solve 13 a and b?

Step-by-step explanation:

Let A=ax²+bx+c

x=1,A=a+b+c or 7=a+b+c   ...(1)

x=2,A=4a+2b+c or 12=4a+2b+c   ...(2)

x=3,A=9a+3b+c or 15=9a+3b+c   ...(3)

subtract (1) from (2) & (3)

3a+b=5   ...(4)

8=8a+2b

or 4a+b=4   ...(5)

subtract (4) from (5)

a=-1

from (4)

-3+b=5

b=5+3=8

b=8

from (1)

-1+8+c=7

c=0

so A=-x²+8x

thus  table shows it is quadratic.

b.

A=-x²+8x=-(x²-8x+16-16)

or A=-(x-4)²+16

vertex is (4,16)

2

step-by-step explanation:

answer: 33 ( approx)

step-by-step explanation:

since, in the linear regression formula, the slope is the a in the equation y = b + ax ( by comparing it with the general equation of line y = mx + c )

where,

here given table is,

price ($), x   :           18         23       25       29       30       33

pairs sold, y :         16         13         10       8         6       2

so, ,   ,   ,

and   ,

thus, slop of the given line is,

⇒  

⇒   ≈ 33