Question

If x2 + 2mx + 4 = 0 has a root x = 2, then the value of m is​

Answer 1

Solution

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Given quadratic equation can be written as, 

x2−(2m)x+(8m−15)=0

Now for equal roots, Discriminant =0

⇒b2−4ac=0

⇒(−2m)2−4(8m−15)=0

⇒m2−8m+15=0

⇒(m−3)(m−5)=0, factor 

⇒m=3,5

Answer 2

Answer:

x2 + 2mx + 4 = 0 has a root x = 2,

${x}^{2} + 2mx + 4 = 0$

Put x = 2

${4}^{2} + 2 \times m \times 2 + 4 = 0 \\ 16 + 4m + 4 = 0 \\ 20 + 4m = 0 \\ m = - 5$