How do you graph quadratic function \[y={{x}^{2}}-4x+7\]?
Answer
611.1k+ views
Hint:
In the given question, we have been asked the steps for plotting a graph of a given quadratic equation. We will plot the graph of a given quadratic equation using vertex form. In order to graph a quadratic using vertex form, first we need to find the vertex of the given equation. Later we will find the y-intercept and the x-intercept and then plot the points we found in the above steps. In this way we can graph a quadratic equation using vertex form.
Complete step by step solution:
We have given that,
\[y={{x}^{2}}-4x+7\]
Converting into vertex form,
We have,
\[y={{x}^{2}}-4x+7\]
Using the vertex form of the equation; i.e.
\[y=a{{\left( x-h \right)}^{2}}+k\]
Where,
\[a\] equals to the coefficient of \[{{x}^{2}}\].
‘h’ is the x-coordinate of the vertex.
‘k’ is the y-coordinate of the vertex.
Vertex of the given equation \[y={{x}^{2}}-4x+7\] is;
Now, solving for the value of ‘x’ and ‘y’,
\[y={{x}^{2}}-4x+7\]
Here ‘a’ is the coefficient of first term and b is the coefficient of ‘x’.
\[\Rightarrow x=\dfrac{-b}{2a}=\dfrac{-\left( -4 \right)}{2}=2\]
\[\Rightarrow x=2\]
Now, solving for the value of ‘y’.
Putting x = -7 in the given equation, we get
\[\Rightarrow y={{\left( 2 \right)}^{2}}-4\left( 2 \right)+7\]
Simplifying the above equation, we get
\[\Rightarrow y=4-8+7=3\]
\[\Rightarrow y=3\]
Therefore, the vertex\[=(2,3)\].
Thus,
Vertex = (2, 3), ‘a’ = 1
Now, substituting these values in the vertex equation form, we obtain
\[y=a{{\left( x-h \right)}^{2}}+k\]
\[y=1{{\left( x-\left( 2 \right) \right)}^{2}}+\left( 3 \right)\]
Simplifying the above, we get
\[y={{\left( x-2 \right)}^{2}}+3\]
Hence, the equation \[y={{x}^{2}}-4x+7\] in vertex form is\[y={{\left( x-2 \right)}^{2}}+3\].
The equation of parabola is in the form \[{{\left( x-a \right)}^{2}}=2p\left( y-b \right)\]
Rewrite the equation in the form of parabola equation,
We have,
\[y={{\left( x-2 \right)}^{2}}+3\]
We can also write it as;
\[{{\left( x-2 \right)}^{2}}=\left( y-3 \right)\]
Here 2p = 1, \[p=\dfrac{1}{2}\]
Thus,
The focus is \[\left( 2,\dfrac{7}{2} \right)\]
The vertex is (2, 3)
Now finding y-intercept
Put x = 0
\[y={{x}^{2}}-4x+7={{0}^{2}}-4\left( 0 \right)+7=7\]
Thus, we get the point i.e. (0, 7)
Plotting the points on the graph we found above,
Therefore, this is the required graph of the \[y={{x}^{2}}-4x+7\].
Note:
Students should be very well aware of the vertex form of the equation. Also, they should know about the concept of converting the given equation into vertex form. They should also be very careful while doing the calculations to avoid making errors. Students should also know to find the coordinates of the vertex.
In the given question, we have been asked the steps for plotting a graph of a given quadratic equation. We will plot the graph of a given quadratic equation using vertex form. In order to graph a quadratic using vertex form, first we need to find the vertex of the given equation. Later we will find the y-intercept and the x-intercept and then plot the points we found in the above steps. In this way we can graph a quadratic equation using vertex form.
Complete step by step solution:
We have given that,
\[y={{x}^{2}}-4x+7\]
Converting into vertex form,
We have,
\[y={{x}^{2}}-4x+7\]
Using the vertex form of the equation; i.e.
\[y=a{{\left( x-h \right)}^{2}}+k\]
Where,
\[a\] equals to the coefficient of \[{{x}^{2}}\].
‘h’ is the x-coordinate of the vertex.
‘k’ is the y-coordinate of the vertex.
Vertex of the given equation \[y={{x}^{2}}-4x+7\] is;
Now, solving for the value of ‘x’ and ‘y’,
\[y={{x}^{2}}-4x+7\]
Here ‘a’ is the coefficient of first term and b is the coefficient of ‘x’.
\[\Rightarrow x=\dfrac{-b}{2a}=\dfrac{-\left( -4 \right)}{2}=2\]
\[\Rightarrow x=2\]
Now, solving for the value of ‘y’.
Putting x = -7 in the given equation, we get
\[\Rightarrow y={{\left( 2 \right)}^{2}}-4\left( 2 \right)+7\]
Simplifying the above equation, we get
\[\Rightarrow y=4-8+7=3\]
\[\Rightarrow y=3\]
Therefore, the vertex\[=(2,3)\].
Thus,
Vertex = (2, 3), ‘a’ = 1
Now, substituting these values in the vertex equation form, we obtain
\[y=a{{\left( x-h \right)}^{2}}+k\]
\[y=1{{\left( x-\left( 2 \right) \right)}^{2}}+\left( 3 \right)\]
Simplifying the above, we get
\[y={{\left( x-2 \right)}^{2}}+3\]
Hence, the equation \[y={{x}^{2}}-4x+7\] in vertex form is\[y={{\left( x-2 \right)}^{2}}+3\].
The equation of parabola is in the form \[{{\left( x-a \right)}^{2}}=2p\left( y-b \right)\]
Rewrite the equation in the form of parabola equation,
We have,
\[y={{\left( x-2 \right)}^{2}}+3\]
We can also write it as;
\[{{\left( x-2 \right)}^{2}}=\left( y-3 \right)\]
Here 2p = 1, \[p=\dfrac{1}{2}\]
Thus,
The focus is \[\left( 2,\dfrac{7}{2} \right)\]
The vertex is (2, 3)
Now finding y-intercept
Put x = 0
\[y={{x}^{2}}-4x+7={{0}^{2}}-4\left( 0 \right)+7=7\]
Thus, we get the point i.e. (0, 7)
Plotting the points on the graph we found above,
Therefore, this is the required graph of the \[y={{x}^{2}}-4x+7\].
Note:
Students should be very well aware of the vertex form of the equation. Also, they should know about the concept of converting the given equation into vertex form. They should also be very careful while doing the calculations to avoid making errors. Students should also know to find the coordinates of the vertex.
Recently Updated Pages
Difference Between Prokaryotic Cells and Eukaryotic Cells

If x a + bt + ct2 where x is in meters and t is in class 11 physics CBSE

A car covers the first half distance between two places class 11 physics CBSE

The resultant of two vectors overrightarrow P and overrightarrow class 11 physics CBSE

Find the value of cos 135 class 11 maths CBSE

A mass M is held in place by an applied force F and class 11 physics CBSE

Trending doubts
One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

Find the value of the expression given below sin 30circ class 11 maths CBSE

Draw a diagram of nephron and explain its structur class 11 biology CBSE

10 examples of friction in our daily life

Proton was discovered by A Thomson B Rutherford C Chadwick class 11 chemistry CBSE

Bond order ofO2 O2+ O2 and O22 is in order A O2 langle class 11 chemistry CBSE

