Q. 553.9( 9 Votes )

Solve each of the following quadratic equations:


Answer :


taking LCM




x2 + 4x - 5 = 7 cross multiplying


x2 + 4x - 12 = 0


Using the splitting middle term - the middle term of the general equation is divided in two such values that:


Product = a.c


For the given equation a = 1 b = 4 c = - 12


= 1. - 12 = - 12


And either of their sum or difference = b


= 4


Thus the two terms are 6 and - 2


Difference = 6 - 2 = 4


Product = 6. - 2 = - 12


x2 + 4x - 12 = 0


x2 + 6x - 2x - 12 = 0


x(x + 6) - 2(x + 6) = 0


(x + 6)(x - 2) = 0


(x + 6) = 0 or (x - 2) = 0


x = - 6 or x = 2


Hence the roots of equation are - 6 or 2.


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