{"id":6683,"date":"2021-10-19T20:08:40","date_gmt":"2021-10-19T14:38:40","guid":{"rendered":"https:\/\/mathemerize.com\/?p=6683"},"modified":"2021-11-27T23:23:34","modified_gmt":"2021-11-27T17:53:34","slug":"relation-between-roots-and-coefficients-of-quadratic-equation","status":"publish","type":"post","link":"https:\/\/mathemerize.com\/relation-between-roots-and-coefficients-of-quadratic-equation\/","title":{"rendered":"Relation Between Roots and Coefficients of Quadratic Equation"},"content":{"rendered":"
Here you will learn what is the relation between roots and coefficients of quadratic equation with examples.<\/p>\n
Let’s begin –<\/p>\n
The general form of quadratic equation is \\(ax^2 + bx + c\\) = 0, a \\(\\ne\\) 0.<\/p>\n
The root of the given equation can be found by using the formula :<\/p>\n
\nx = \\(-b \\pm \\sqrt{b^2 – 4ac}\\over 2a\\)<\/p>\n<\/blockquote>\n
Relation Between Roots and Coefficients of Quadratic Equation<\/h2>\n
(a) Let \\(\\alpha\\) and \\(\\beta\\) be the roots of the quadratic equation \\(ax^2 + bx + c\\) = 0, then<\/p>\n
\n(i) Sum of roots<\/strong> is \\(\\alpha\\) + \\(\\beta\\) = \\(-b\\over a\\)<\/p>\n
(ii) Product of roots <\/strong>is \\(\\alpha\\) \\(\\beta\\) = \\(c\\over a\\)<\/p>\n
(iii)<\/strong> \\(|\\alpha – \\beta|\\) = \\(\\sqrt{D}\\over | a |\\)<\/p>\n
where D = \\(b^2 – 4ac\\)<\/p>\n<\/blockquote>\n
(b) A quadratic equation whose roots are \\(\\alpha\\) and \\(\\beta\\) is \\((x – \\alpha)\\) \\((x – \\beta)\\) = 0 i.e.<\/p>\n
\n\\(x^2 – (\\alpha + \\beta)x + \\alpha\\beta\\) = 0<\/p>\n
i.e. \\(x^2\\) – (sum of roots) x + product of roots = 0.<\/p>\n<\/blockquote>\n
Example<\/span><\/strong> : If \\(\\alpha\\) and \\(\\beta\\) are the roots of a quadratic equation \\(x^2 – 3x + 5\\) = 0. Find the sum of roots and product of roots.<\/p>\n
Solution<\/span><\/strong> : We have, \\(x^2 – 3x + 5\\) = 0<\/p>\n
Sum of Roots = \\(\\alpha\\) + \\(\\beta\\) = \\(-b\\over a\\) = 3<\/p>\n
Product of Roots = \\(\\alpha\\)\\(\\beta\\) = \\(c\\over a\\) = 5<\/p>\n
Example<\/span><\/strong> : Find the quadratic equation whose sum of roots is 5 and product of roots is 6.<\/p>\n
Solution<\/span><\/strong> : By using the formula,<\/p>\n
\\(x^2\\) – (sum of roots) x + product of roots = 0.<\/p>\n
\\(x^2 – (5)x + (6)\\) =0 \\(\\implies\\) \\(x^2 – 5x + 6\\) = 0<\/p>\n\n\n