if the zero of the quadratic polynomial x2+(a+1)x+b are 2and -3 then find a and b
Answers
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if the zero of the quadratic polynomial x²+(a+1)x+b are 2 and -3 then find a and b.
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x²+(a+1)x+b = 0
★ In 1st case , putting x = 2 in the equation ★
x²+(a+1)x+b = 0
→ 2² + (a+1)×2 + b = 0
→ 4 + 2a+2 + b = 0
→ 2a + b = -6....................(i)
★ In 2nd case, putting x= -3 in the equation★
x²+(a+1)x+b = 0
→(-3)² + (a+1) ×(-3) + b = 0
→ 9 - 3a - 3 +b = 0
→ - 3a +b = -6
→ 3a - b = 6................(ii)
2a+b = -6
3a - b = 6
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5a = 0
→ a = 0
✞putting a= 0 in (i) no. equation✞
2a + b = -6
→ 2×0 + b = -6
→ b = -6
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a = 0
b = -6
a = 0
b = -6
- the zero of the quadratic polynomial x²+(a + 1)x + b.
- find a and b.
- x²+(a + 1)x + b
x²+(a + 1)x + b
2²+(a + 1)² + b = 0
4 + 2a + 2 + b = 0
2a + b = -6_____(1)
putting x = -3 in the equation.
x²+(a + 1)x + b
-3²+(a + 1)-3 + b = 0
9 - 3a - 3 + b = 0
3a + b = -6_____(2)
By Elimination
2a + b = -6
3a + b = -6
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5a = 0
a = 0
putting a = 0 in equation (1).
2a + b = -6
2(0) + b = -6
0 + b =-6
hence,
a = 0
b = -6