What is the value of #k#, given that one solution of the equation #5x^2-kx+40=0# is #4/5#?

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Answer 1 · 2016-10-01T11:27:13

This condition is satisfied for #k=54#

To find the value of #k# for which #4/5# is a solution of this equation we have to substitute #4/5# for #x# and solve the resulting equation for #k#:

#5xx(4/5)^2-4/5k+40=0#

#5xx16/25-4/5k+40=0#

#16/5-4/5k+40=0#

#4/5k=40+3 1/5#

#4/5k=216/5#

#4k=216#

#k=54#