If the zeroes of the cubic polynomial x3 – 6x2 + 3x + 10 are of the form a,a + b and a + 2b for some real numbers a and b, find the values of a and b . *
Answers
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Step-by-step explanation:
clearly x=2 is a solution of the eqn
factorising the eqn we get
X3 -2x2 -4x2 + 8x - 5x + 10 = 0
x2(x-2) - 4x(x-2) - 5(x-2) = 0
(x-2)(x2 -4x - 5) = 0
this gives
x-2 = 0, x= 2
x2 - 4x - 5 = 0
x2 - 5x + x - 5 = 0
x(x-5) + 1(x-5) = 0
(x-5)(x+1) = 0
x = -1, 5
so roots are -1, 2 and 5
case 1
a = -1 and a + b = 2
which gives b = 2 - a = 3
a + 2b = 5 which is satisfied with the values of a= -1 and b = 3.
hence a= -1, b =3 is a solution
case 2
a = -1 and a+b = 5
this gives b = 6
but a+2b = 2 is not satisfied with the value of a= -1 and b = 6, so is not a solution
case 3
a= 2 and a+b= -1
this gives b = -3
but a+2b = 5 is not satisfied with these vues, so is not a solution
case 4
a = 2 and a+b = 5
this gives b = 3
but a+2b = -1 is not satisfied hence is not a solution
case 5
a = 5 and a+b = 2
this gives b = -3
a+2b = -1 is satisfied with these values hence
a= 5 and b= -3 is also a solution
case 6
a= 5 and a+b = -1
this gives b= -6
a+2b = 2 is not satisfied with these values hence not a solution
hence the solutions in real numbers are
1. a= -1, b = 3
2. a = 5, b = -3