Question

Find the value of k for wich pair of quadratic equation 4x^+5kx +25=0 has equal roots

Answer 1

for equal roots,

b^2-4ac=0

here b=5k, a=4 ,c=25

5k^2 -4(4*25)=0

25k^2-400=0

25k^2=400

k^2=400/25

therefore, k=20/5=4

value of k is 4