Question 182933: Please I need help with: quintun was solving a quadestic equation in the form ax^2+bx+c=0 using the quadestic formula. He made the mistake, however, of switching a and c in the formula and and as a result he got answers that were 3 times the correct answer. Find the product of the roots of the quadratic equation
Answer by Edwin McCravy(20054) (Show Source):
You can put this solution on YOUR website! Please I need help with: quintun was solving a quadestic equation in the form ax^2+bx+c=0 using the quadestic formula. He made the mistake, however, of switching a and c in the formula and and as a result he got answers that were 3 times the correct answer. Find the product of the roots of the quadratic equation.
For any quadratic equation of the form
,
the product of the two roots is .
Suppose the two roots are and
Then
When he switched and in the
quadratic formula, he got the roots for
,
to be and
So their product is ,
and that had to equal the number
so
So we have the system:
Clearing of fractions:
Solving each for the product
So we have
cross-multiplying gives:
or
so, factoring,
So either or
Now in the first case, substitution of
of for in
gives
---
In the second case, substitution of
of for in
gives
So the product of the roots is either
or
Those are the answers!
----------------------------------------
If you want to demonstrate those answers in
specific cases, solve the quadratic equation:
and you'll find the solutions
and and which have
product
Then switch and and you'll
get the equation
and you'll find that it has
solutions and which
are 3 times the solutions and .
Edwin
|
|
|