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\left. \begin{array} { l } { \text { (a) } 21 x ^ { 2 } - 147 x + 20 = 0 } \\ { \text { b) } 21 x ^ { 2 } + 147 x + 20 = 0 } \\ { \text { c) } 21 x ^ { 2 } - 147 x - 20 = 0 } \end{array} \right. |
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Answer» Any quadratic equation having zeroes a and b can be written asx² - (a+b)x + ab = 0we have given a+b = 3 and a³ + b³ = 7so we know (a+b)³ = a³+b³ +3ab(a+b)27 = 7 + 3ab(3)20 = 9 abab = 20/9soEquation is x² -3x+20/9 = 09x² -27x +20 = 0no given option is correct pls give correct reply |
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