SOLUTION: Find the value ok kso that the equation 3x^2-(5+k)x - 17 = 0 will have equal roots roots..

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Question 1122375: Find the value ok kso that the equation 3x^2-(5+k)x - 17 = 0 will have equal roots roots..
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Discriminant equal 0.

%28-%285%2Bk%29%29%5E2-4%2A3%2A%28-17%29=0
Simplify this and solve for k.

%28-1%29%5E2%285%2Bk%29%5E2%2B12%2A17=0
k%5E2%2B10k%2B25-12%2A17=0
k%5E2%2B10k-179=0, and 179 is a prime number;

k=%28-10%2B-+sqrt%28100%2B4%2A%28179%29%29%29%2F2, general solution for quadratic equation
k=%28-10%2B-+sqrt%28816%29%29%2F2
k=%28-10%2B-+sqrt%2816%2A51%29%29%2F2
k=%28-10%2B-+4%2Asqrt%2851%29%29%2F2
highlight%28k=-5%2B-+2%2Asqrt%2851%29%29