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2. Which quadratic function has a graph that passes through the points (-1, 4), (2, -5), and (4, 9)? A O f(x) = 0.522 - 3.5x B f(x) = -2x2 - 2 + 5 CO f(3) = 2? + 7x + 10 D. O f() = 2x2 - 5x - 3

2. Which quadratic function has a graph that passes through the points (-1, 4), (2, -5), and-example-1
User Valaer
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1 Answer

1 vote

The given coordinate on the graph is (-1,4), (2,-5) and (4,9).

The general form of the quadratic equation is,


y=ax^2+bx+c

Substituting the given coordinates in the general equaion,


\begin{gathered} 4=a-b+c\ldots.\ldots\text{.}(1) \\ -5=4a+2b+c\ldots\text{.}(2) \\ 9=16a+4b+c\ldots.\text{.}(3) \end{gathered}

Substracting (1) from (2),


\begin{gathered} 3a+3b=-9 \\ a+b=-3\ldots(4) \end{gathered}

Substracting (1) from (3),


\begin{gathered} 15a+5b=5 \\ 3a+b=1\ldots\text{.}(5) \end{gathered}

Substracting (4) from (5),


\begin{gathered} 2a=4 \\ a=2 \end{gathered}

Substituting in equation (5),


\begin{gathered} 3(2)+b=1 \\ b=-5 \end{gathered}

Substititing in equation (1),


\begin{gathered} 4=2-(-5)+c \\ c=-3 \end{gathered}

Substituting the value of a,b,c in general equation,


y=2x^2-5x-3

Thus, option (D) is the correct solution.

User AlameerAshraf
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