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Use the quadratic formula to solve the equation 2k(k+5)= -25

User Stanni
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So, we need to solve the quadratic equation from quadratic formula as per the question, but before starting, let's first recall that, for any quadratic equation of the form ax² + bc + c = 0, the discriminant is given by D = b² - 4ac, and the value of x is given by :


  • {\boxed{\bf{x=(-b\pm √(D))/(2a)}}}

Also, their are no real solutions of x i.e their are only imaginary values of x iff D < 0, equal and real roots iff D = 0 and real and distinct roots iff D > 0. So, let's convert the given equation to the standard form ax² + bx + c = 0 and then we will find the discriminant and then we will be solving for k ;


{:\implies \quad \sf 2k(k+5)=-25}


{:\implies \quad \sf 2k^(2)+10k=-25}


{:\implies \quad \sf 2k^(2)+10k+25=0}

Now, on comparing this with the standard equation, we will get a = 2, b = 10 and c = 25, and then D = (10)² - 4 × 2 × 25 = 100 - 200 = - 100, now as D < 0, so their will be imaginary values of k, so now solving for k will yield by using the Quadratic Formula ;


{:\implies \quad \sf k=(-10\pm √(-100))/(2* 2)}


{:\implies \quad \sf k=(-10\pm 10\iota)/(2* 2)}


{:\implies \quad \sf k=(2(-5\pm 5\iota))/(2* 2)=(-5\pm 5\iota)/(2)}


{:\implies \quad \boxed{\bf{k=(-5+5\iota)/(2)\:\:,\:\: (-5-5\iota)/(2)}}}

This is the required answer

User CrepeGoat
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