Graphs
Graphical method of Solving Quadratic Equations
So far, we have learnt to solve a quadratic equation using the method of factorisation and using the quadratic formula. Apart from using these methods, quadratic equations can also be solved graphically.
Let us learn this method by taking the quadratic equation x^{2} – 9 = 0.
Here, x^{2} – 9 = 0
⇒ x^{2} = 9
Let y = x^{2} = 9
⇒y = x^{2} and y = 9
Step I:
Write the values of x and y that satisfy y = x^{2} in a table.
x |
y |
–3 |
(–3)^{2} = 9 |
–1 |
(–1)^{2} = 1 |
0 |
0^{2} = 0 |
1 |
1^{2} = 1 |
3 |
3^{2}= 9 |
Step II:
Choose the appropriate scale.
For y = x^{2} and y = 9, let us choose the scale on the x and y–axis as 1 cm = 1 unit.
Step III:
Plo…
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