Question

Write the equation, in standard form, of the parabola containing the following points:
(0, 1), (1, 5), (2, 3). You must set up a system of three equations to get credit for this question.
A. y= -3x^2+7x+1
B. y= -7x^2+3x+1
C. y= -x^2+5x+3
D. y= 3x^2-7x-1

Answer 1

i think B but idk 4 sure

Answer 2

first try (0,1) in each
Immediately it has to be A or B to get 1 when x = 0
now try (1,5 ) in A and B
-3+7 + 1 = 5 ok
-7 + 3 + 1 = -3 No way
Better be A try (2,3) inA
-3*4 + 14 +1
-12+ 14 +1 = 3 !!!! Caramba !!!!

Answer 3

Now the way they want
y = a x^2 + b x + c
(0,1) 1 = 0 + 0 + c so c = 1
so
y = a x^1 + b x + 1
(1,5) 5 = a + b + 1
so b = 4-a
so
y = a x^2 + (4-a) x + 1
(2,3) 3 =a *4 + (4-a) * 2 + 1
3 = 4 a + 8 - 2a + 1
-6 = 2a
a = -3
b = 4-a = 7
c = 1 What else is new :)