if the zeros of a cubic polynomial x cube minus 6 X square + 3 X + 10 hour of the form a a + b and a + 2B for some real numbers A and B find the values of A and B as well as zeros of the given polynomial
Answers
Answered by
4
,
Given cubic polynomial is
p(x)=x³−6x²+3x+10
The zeros of the polynomial p(x) are of the form a, a+b and a+2b
Then,
a+a+b+a+2b=− −6/1
=>3a+3b=6
=>a+b=2 ----------------(i)
Also, a(a+b)+(a+b)(a+2b)+a(a+2b)= 3/1
=>a²+ab+a ² +2ab+ab+2b²+a²+2ab=3
=>3a ² +2b ² +6ab=3 ----(ii)and
a(a+b)(a+2b)=−10/1
=>a³+a ² b+2a²b+2ab²=10
From (i), b=2−a
Putting this value in (ii), we get
=>3a ²+2(2−a) ²+6a(2−a)=3
=>3a ² +2(4−4a+a ² )+12a−a ²=3
=>−a ²+4a+5=0
=>a ² −4a−5=0
=>a² −5a+a−5=0
=>a(a−5)+(a−5)=0
=>.(a−5)(a+1)=0
=>a=5 or a=−1
=>b=−3 or b=3 respectively
From equation (iii), we get
at a=5, b=−3
=>5 ³+(5) ²(−3)+2(5) ²(−3)+2(5)(−3) ²
=−10
=>125−75−150+90=−10
=>−10=−10 which is true.
and at a=−1, b=3, we have
=>(−1) ³ +(−1) ² 3+2(−1) ² (3)+2(−1)(3)²
=−10
=>−1+3−6−18=10
=>−22=−10 which is not true.
Thus, a=5, b=−3
Zeros of the polynomial are 5, 5−3, 5−2×3 ie 5,2,−1
Answered by
1
Answer:
here it is hope it's helpful for you .
Step-by-step explanation:
x³-6x²+3x+10
sum of the zeroes = -b/a
a + a+b + a+2b = -(-6) / 1
3a +3b = 6
3(a+b) = 6
a+b = 2. 1eq.
product of zeroes = c/a
a(a+b) + (a+b)(a+2b) + (a+2b)a = 3/1
a²+ab+ a²+ 2b² + 2ab +ab + a² +2ab = 3
3a² + 2b² + 6ab = 3
from 1 eq we can say that a = 2-b
3(2-b)² + 2b² +6(2-b)b = 3
3(2²+b²-4b) +2b² + 6(2b-b²) = 3
3(4+b²-4b) +2b² + 6(2b-b²) = 3
12 + 3b² -12b + 2b² +12b -6b² = 3
-b²+12 = 3
-b² = -9
b = 3 hence we can find a from 1eq.
a+b = 2
a+3 = 2
a= -1
so the zeroes are
a= -1
a+b = -1+3 = 2
a+2b = -1 +2(3) = 5
Similar questions