Pages

Find the value of p for which one root of the quadratic . . .

Question : Find the value of p for which one root of the quadratic equation px²-14x+8=0 is 6 times the other.

Doubt by Utkrisht

Solution : 
β=6α (Given)
px²-14x+8=0
a=p
b=-14
c=8
α+β=-b/a
α+β=-(-14)/p
α+β=14/p
α+6α=14/p [∵β=6α]
7α=14/p
α=2/p — (1)

αβ=c/a
αβ=8/p
α(6α)=8/p [β=6α]
6
α²=8/p
6[
2/p]²=8/p [From equation (1)]
(6×4)/p²=8/p
24/p²=8/p
3/p=1
3=p
p=3