Question

Type the correct answer in the box. Write the standard form of the quadratic equation modeled by the points shown in the table below.
x y
-1 14
0 7
1 4
2 5
3 10

Answer: y =

Answer 1

Y =ax² + bx +c

1) Point (0,7)

7 = a*0² +b*0 +c
c = 7
y=ax² + bx + 7

2) Point (1,4)
4=a*1² + b*1 + 7, ----> 4 = a +b + 7, ------> a+b= - 3
3) Point (2, 5)
5=a*2² + b*2 + 7, ----> 5=4a+2b +7,---> -2=4a+2b, ----> -1=2a + b

4)  a+b= - 3, ----> b= -3 - a (substitute in the second equation)
    2a+b= -1
2a - 3 - a = -1, ----> a - 3 = -1, a =2

5) a+b= - 3
    2 + b = -3
b = -5

y=2x² - 5x + 7