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## One of the roots of equation 5m2 + 2m + k = 0 is  $-7\over5$ .Complete the following activity to find the value of ’k’.Solution :  ......... is a root of quadratic equation 5m2 + 2m + k = 0                 Put m = .........   in the equation.                 5 * .........2  + 2 * ......... + k=0                  .........+.........+ k = 0                 .........+ k = 0                 k =.........

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Sol.   $-7\over5$   is a root of quadratic equation 5m2 + 2m + k = 0

∴        Put m = $-7\over5$  in the equation.

5 ×$({-7\over5})^2$ + 2 × $-7\over5$ + k = 0

∴                   $49\over 5$ + $({-14\over 5})$ + k = 0

∴                             $49 – 14\over 5$ + k = 0

∴                                 $35\over 5$ + k = 0

∴                                   7 + k = 0
∴                                         k = –7

uÉaÉïxÉqÉÏMüUhÉ August 24 , 2018 0 Comments 123 views