Question

How do you do solve 13 a and b?

Answer 1

Answer:

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)

Answer 2

For a you have to find the formula. for ex. 1+x=7 so you solve for x.