Question

find the values of k for which 2/5 is one root of the quadratic equation 5x2-kx+6​

Answer 1

Answer:

$let \: x = 2 \div 5 \\ {5x}^{2} - kx + 6 \\ 5 \times( 2 \div 5)^{2} - k \times 2 \div 5 + 6 = 0 \\ 5 \times 4 \div 25 - 2k \div 5 + 6 = 0 \\ 4 \div 5 - 2k \div 5 + 6 \times 5 \div 1 \times 5 = 0 \\ 4 - 2k + 30 \div 5 = 0 \\ 4 - 2k + 30 = 0 \times 5 \\ 4 - 2k + 30 = 0 \\ 4 + 30 = 2k \\ 34 \div 2 = k \\ k = 17$