Quadratic Equation
- With respect to the roots of x2 - x - 2 = 0, we can say that :
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Given :- x2 - x - 2 = 0
The given equation is of the form
ax2 + bx + c = 0
Here , a = 1 , b = -1 , c = - 2Correct Option: B
Given :- x2 - x - 2 = 0
The given equation is of the form
ax2 + bx + c = 0
Here , a = 1 , b = -1 , c = - 2
Now, D2 = b2 - 4ac = ( -1 )2 - 4 x 1 x ( - 2 )
D = √9 = 3
So, roots are rational .
Hence, both the roots must be integers.
- The roots of the equation √7x2 - 6x - 13√7 = 0 are
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Given that :- √7x2 - 6x - 13√7 = 0
⇒ √7x2 - 13x + 7x - 13√7 = 0
⇒ x( √7x - 13 ) + √7( √7x - 13 ) = 0
⇒ ( x + √7 ) ( √7x - 13 )
⇒ x + √7 = 0 or √7x - 13 = 0⇒ x = - √7 or x = 13 = 13 √7 √7 7 Correct Option: C
Given that :- √7x2 - 6x - 13√7 = 0
⇒ √7x2 - 13x + 7x - 13√7 = 0
⇒ x( √7x - 13 ) + √7( √7x - 13 ) = 0
⇒ ( x + √7 ) ( √7x - 13 )
⇒ x + √7 = 0 or √7x - 13 = 0⇒ x = - √7 or x = 13 = 13 √7 √7 7 Thus, the two roots of given quadratic equation are - √7 and 13 √7 . 7
- In the following, find the value (s) of P so that the given equation has equal roots 3x 2 - 5x + P = 0
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The given quadratic equation is
3x2 - 5x + P = 0
Comparing with ax 2 + bx + c = 0, we get
a = 0, b = - 5, c = P
If the given quadratic equation has equal roots then its discriminant = 0Correct Option: C
The given quadratic equation is
3x 2 - 5x + P = 0
Comparing with ax 2 + bx + c = 0, we get
a = 0, b = - 5, c = P
If the given quadratic equation has equal roots then its discriminant = 0
⇒ b 2 - 4ac = 0
⇒ ( - 5 ) 2 - 4 x (3) x (P) = 0
⇒ 25 - 12P = 0⇒ P = 25 12
Hence , required answer is option C .
- √6 + √6 + √6 +........ is equal to
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As per the given above question , we have
Let, x = 6 + √6 + √6 + √6 +........
On squaring both sides, we have
x2 = 6 + √6 + √6 + √6 +........
⇒ x2 = 6 + x
⇒ x2 - x - 6 = 0Correct Option: D
As per the given above question , we have
Let, x = 6 + √6 + √6 + √6 +........
On squaring both sides, we have
x2 = 6 + √6 + √6 + √6 +........
⇒ x2 = 6 + x
⇒ x2 - x - 6 = 0
⇒ x2 - 3x + 2x - 6 = 0
⇒ x( x - 3 ) + 2( x - 3 ) = 0
⇒ ( x - 3 ) ( x + 2 ) = 0
⇒ x = 3 and x ≠ −2 because numbers are positive.
Thus , correct answer will be 3 .
- If α, β are the roots of the quadratic equation x2 - 8x + k = 0, find the value of k such the α2 + β2 = 40
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According to question ,
∵ α, β are the roots of the equation x2 - 8x + 1 = 0∴ α + β = - b = - ( - 8 ) = 8 a 1 and αβ = c = k = k a 1
Now, α2 + β2 = ( α + β )2 - 2αβ
Correct Option: A
According to question ,
∵ α, β are the roots of the equation x2 - 8x + 1 = 0∴ α + β = - b = - ( - 8 ) = 8 a 1 and αβ = c = k = k a 1
Now, α2 + β2 = ( α + β )2 - 2αβ
⇒ 40 = (8)2 -2k ⇒ 2k= 24 ⇒ k = 12.
Thus , the value of k is 12 .