We'll use Viete's relations and we'll form the quadratic
when we know the sum and the product of the roots:
x1 + x2
= 5/3 + 3/5
x1 + x2 = (25 +
9)/15
x1 + x2 =
34/15
S = x1 + x2 =
34/15
x1*x2 =
(5/3)*(3/5)
x1*x2 =
1
P =
1
We'll form the quadratic, knowing the
values of the sum and the product:
x^2 - Sx + P =
0
x^2 - 34x/15 + 1 = 0
We'll
multiply by 15 and we'll get the final form of the quadratic whose sum is 34/15 and
product is 1.
15x^2 - 34x + 15 =
0
We also could use the fact
that a quadratic equation could be written as a product of linear factors, when the
solutions are given.
ax^2 + bx + c = (x -
5/3)(x -3/5)
We'll remove the
brackets;
ax^2 + bx + c = x^2 - 3x/5 - 5x/3 +
1
We'll combine like terms and
we'll
get:
ax^2
+ bx + c = x^2 - 34x/15 +
1
No comments:
Post a Comment