Question

I need help to solve this

Answer 1

Answer:

Step-by-step explanation:

The catch is to put this into the quadratic and solve for a b and c in three equations.

x = 1

a(1)^2 + b(1) + c= 0            

a + b + c + 0                (1)

x = - 1

a(-1)^2 + b(-1) + c = 2

a - b + c = 2                 (2)

x = 2

a(2)^2 + b(2) + c = 8

4a + 2b + c = 8            (3)

===================

Add 1 and 2 together

a + b + c = 0

a - b + c = 2

2a + 2c = 2           Divide by 2

a + c = 1                       (4)  

=====================

Multiply (2) by 2

2a - 2b + 2c = 4          (5)

======================

Add (5) + (3)

2a - 2b + 2c = 4

4a + 2b + c = 8

6a + 3c = 12               (6)

=====================

Multiply (4) by 3

3a + 3c = 3                 (7)

===================

Subtract (7) from (6)

6a + 3c = 12

3a + 3c =  3

3a = 9                      Divide by 3

3a/3 = 9/3

a = 3

=============

Use (4) to find c

a + c = 1

3 + c = 1                  Subtract 3 from both sides

3-3 + c = 1-3

c = - 2

=================

Use 1 to find b

3 + b - 2 = 0          Combine 3 and -2

1 + b = 0                Subtract 1 from both sides

b = - 1              

====================

Answers

a = 3

b = - 1

c = - 2