Question

It is known that x1 and x2 are roots of the equation x^2−8x+k=0, where 3x1+4x2=29. Find k.

Answer 1

we know that x1 + x2= 8

x1x2 = k. ....1

and it is given that

3x1+4x2=29. ....2

from eqn 1

x2 = 8-x1

put it in 2

we get x1=3

and then x2=5

and x1x2=15 which is equal to k