if 2and-3 are the zeroes of x²+(a+1)x+b then find the values of a and b
Answers
Answered by
6
Given :
Given that, 2 and -3 are the zeroes of the polynomial x²+(a+1)x+b.
To find :
We should the values of a and b.
Solution :
Here, the given polynomial x²+(a+1)x+b is in the form of a quadratic equation where :
- a = 1
- b = (a+1)
- c = b
Sum of the zeroes = -b/a
- -(a+1)/1 = 2 + (-3)
- -a-1 = 2 - 3
- -a-1 = -1
- a = 0
Product of zeroes = c/a
- b/1 = 2 × (-3)
- b/1 = -6
- b = -6
Verification :
Let's substituting the values along with the zeroes and verify :
- x²+(a+1)x+b = 0
- (2)²+(0+1)(2)+(-6) = 0
- 4+(1)(2)-6 = 0
- 4+2-6 = 0
- 6-6 = 0
- LHS = RHS
Henceforth, verified!
Answered by
2
- put 2 in p(x) = x² + (a+1)x + b
- p(2) = (2)² + (a+1)(2) + b = 0
- 4 + 2a + 2 + b = 0
- 2a + b + 6 = 0
- 2a = -(b + 6)
- a = -(b+6)/2 → eq(1)
- then ,
- put -3 in p(x) = x² + (a+1)x + b
- then ,
- (-3)² + (a+1)(-3) + b = 0
- 9 + -3a -3 + b = 0
- b - 3a = -9 + 3
- b = 3a + 6 = 3(-(b+6)/2) + 6 = (-3b-18+12)/2
- 2b = -3b - 6
- 2b + 3b = -6
- 5b = -6
- b = -⅚
- now put b = -⅚
- a = -(-⅚+6)/2 = (41/6)/2 = 41/6 × 2 = 41/3
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