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Answers
Given :-
4x² - x - 5
To Find :-
Zeroes of following quadratic polynomials and verify the relationship between the zeroes and the co-effecient
Solution :-
4x² - x - 5
By discrimination method
x = -b ± √(b² - 4ac)/2a
x = -1 ± √[1 - (4)(4)(-5)]/2(4)
x = -1 ± √[1 - (-80)]/8
x = -1 ± √[1 + 80]/8
x = -1 ± √[81]/8
x = -1 ± 9/8
Either
x = 1
or
x = -5/4
Verification
α + β = -b/a
1 + -5/4= -(1)/4
4 - 5/4 = -1/4
-1/4 = -1/4
Now,
αβ = c/a
1 × -5/4 = -5/4
-5/4 = -5/4
Answer
Zeroes are 5/4 and -1
Step-by-step explanation:
Given Quadratic equation → 4x² - x - 5
For finding the zeroes of a quadratic equation first find 2 numbers such that:
- Their product is -20
- Their sum is -1
The 2 numbers which satisfies these conditions are:
4 and -5
Now, factorise it by splitting the middle term.
4x² - x - 5 = 0
→ 4x² + 4x - 5x - 5 = 0
→ 4x (x + 1) - 5 (x + 1) = 0
→ (4x - 5) (x + 1) = 0
So,
- (4x - 5) = 0 → x = 5/4
- (x + 1) = 0 → x = -1
So, the factors are 5/4 and -1
Finding the sum of Zeroes:
α + β = -b/a
→ α + β = 1/4
→ 5/4 - 1 = 1/4
→ 5/4 - 4/4 = 1/4
→ 1/4 = 1/4
Hence, the sum of Zeroes are verified.
Finding the product of zeroes:
αβ = c/a
→ αβ = -5/4
→ 5/4 × -1 = -5/4
→ -5/4 = -5/4
Hence the product of zeroes are verified.