find the numerical difference of the roots of equation x2-7x-18=0
Answers
Answer:
Here,
x² - 7x - 18 = 0
0 has no value
So,
x² - 7x - 18
Here we have to find just root difference of
x² - 7x - 18
=x² + 2x - 9x - 18
= x(x + 2) -9 (x + 2)
= (x+2)(x-9)
So,
Root difference is
So the answer is above
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Given a quadratic equation x^2-7x-18=0, find the difference between its root.
Explanation:
Given a quadratic equation of the form ax^2+bx+c=0 where a, b and c are real numbers having roots \alpha, \beta is given by, \alpha=\frac{-b+\sqrt{b^2-4ac} }{2a} \ \ \ \ \ \ \ \ \ \ \ \ \beta=\frac{-b-\sqrt{b^2-4ac} }{2a}
Hence for the difference of roots \alpha-\beta we get, \alpha-\beta=\frac{-b+\sqrt{b^2-4ac} }{2a} -\frac{-b-\sqrt{b^2-4ac} }{2a}\\->\alpha-\beta=\frac{\sqrt{b^2-4ac} }{a} -----(a)
now we have the equation x^2-7x-18=0 where, a=1,\ b=-7\ and\ c=-18
hence from (a) we get the difference of the roots as, \alpha-\beta=\sqrt{(-7)^2-4(1)(-18)} \\->\alpha-\beta=\sqrt{49+72}\\->\alpha-\beta=\sqrt{121}\\->\alpha-\beta=11
The numerical difference of the roots is 11.