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Answers
Step-by-step explanation:
Given :-
The ratio of the two roots of ax²+bx+c = 0 is 1:r and a≠0
To find :-
Show that (r+1)²/r = b²/ac.
Solution :-
Given quadratic equation is ax²+bx+c = 0
a ≠ 0
Let P(x) = ax²+bx+c = 0
Let the roots of P(x) be A and B
We know that
Sum of the roots = -b/a
=> A + B = -b/a --------(1)
Product of the roots = c/a
=> A×B = c/a -------(2)
The ratio of the roots = A:B
According to the given problem
Ratio of the roots of P(x) = 1:r
=> A:B = 1:r
=> A/B = 1/r
=> 1/r = A/B
=> r = B/A ----------(3)
Now,
On taking LHS = (r+1)²/r
=> [(B/A)+1]²/(B/A)
=> [(B+A)/A]²/(B/A)
=> [(A+B)/A]²/(B/A)
=> [(A+B)²/A²]/(B/A)
=> [(A+B)²/A²]×(A/B)
=> [(A+B)²×A]/[(A²×B)]
=> (A+B)²/(AB)
From (1)&(2)
=> (-b/a)²/(c/a)
=> (b²/a²)/(c/a)
=> (b²/a²)×(a/c)
=> (b²×a)/(a²×c)
=> b²/ac
=> RHS
=> LHS = RHS
Hence, Proved.
Answer:-
If The ratio of the two roots of ax²+bx+c = 0 is 1:r and a≠0 then (r+1)²/r = b²/ac.
Used formulae:-
- The standard quadratic equation is ax²+bx+c = 0
- Sum of the roots = -b/a
- Product of the roots = c/a