Quadratic Equation
- If one root of the quadratic equation 2x2 + Px + 4 = 0 is 2, find the second root and value of P.
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Here ,The given equation is 2x2 + Px + 4 = 0 .......( ⅰ )
⇒ P(x) = 0 , where P(x) = 2 2 + Px + 4 = 0
If 2 is a root of P(x) = 0, then P(2) = 0
Putting x = 2 in equation ( ⅰ ) , we get
⇒ 2(2)2 + P(2) + 4 = 0
⇒ 8 + 2P + 4 = 0
⇒ 2P = - 12⇒ P = -12 = - 6 2 Correct Option: A
Here ,The given equation is 2x2 + Px + 4 = 0 .......( ⅰ )
⇒ P(x) = 0 , where P(x) = 2 2 + Px + 4 = 0
If 2 is a root of P(x) = 0, then P(2) = 0
Putting x = 2 in equation ( ⅰ ) , we get
⇒ 2(2)2 + P(2) + 4 = 0
⇒ 8 + 2P + 4 = 0
⇒ 2P = - 12
Hence the given equation is⇒ P = -12 = - 6 2
2x2 - 6x + 4 = 0 { ∴ Putting the value of P in eq. ( ⅰ ) }
⇒ 2x2 - 2x - 4x + 4 = 0
⇒ 2x ( x - 1 ) - 4( x - 1 ) = 0
⇒ 2( x - 2 ) ( x - 1 ) = 0
⇒ x = 1 or x = 2
Hence second root is 1.
Direction: In the following questions two equations numbered I and II are given. You have to solve both the equations and give answer
( 1 ) if x > y
( 2 ) if x ≥ y
( 3 ) if x < y
( 4 ) if x ≤ y
( 5 ) if x = y or the relationship cannot be established.
- Ⅰ. x2 - 1 = 0
Ⅱ. y2 + 4y + 3 = 0
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From the given equations , we know that
Ⅰ. x2 - 1 = 0
⇒ x2 = 1
Ⅱ. y2 + 4y + 3 = 0
⇒ y2 + y + 3y + 3 = 0
⇒ y( y + 1) + 3( y + 1) = 0Correct Option: B
From the given equations , we know that
Ⅰ. x2 - 1 = 0
⇒ x2 = 1
⇒ x = ± √1 = ± 1
Ⅱ. y2 + 4y + 3 = 0
⇒ y2 + y + 3y + 3 = 0
⇒ y( y + 1) + 3( y + 1) = 0
⇒ ( y + 1) ( y + 3)
⇒ y = -3 or -1
From above equations it is clear that x ≥ y is correct answer .
- Ⅰ. x3 - 371 = 629
Ⅱ. y3 - 543 = 788
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According to given question , we have
Ⅰ. x3 - 371 = 629
⇒ x = √1000 = 10
Ⅱ. y3 - 543 = 788
⇒ y = √1331 = 11Correct Option: C
According to given question , we have
Ⅰ. x3 - 371 = 629
⇒ x = √1000 = 10
Ⅱ. y3 - 543 = 788
⇒ y = √1331 = 11
From above both equations it is clear that x < y is correct answer .
- Ⅰ. 2x2 + 11x + 12 = 0
Ⅱ. 5y2 + 27y + 10 = 0
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According to question ,we can say that
From equation Ⅰ. 2x2 + 11x + 12 = 0
⇒ 2x2 + 8x + 3x + 12 = 0
⇒ 2x( x + 4) + 3( x + 4) = 0
From equation Ⅱ. 5y2 + 27y + 10 = 0
⇒ 5y2 + 25y + 2y + 10 = 0
⇒ 5y( y + 5 ) + 2( y + 5 ) = 0Correct Option: E
According to question ,we can say that
From equation Ⅰ. 2x2 + 11x + 12 = 0
⇒ 2x2 + 8x + 3x + 12 = 0
⇒ 2x( x + 4) + 3( x + 4) = 0
⇒ ( 2x + 3) ( x + 4) = 0
From equation Ⅱ. 5y2 + 27y + 10 = 0∴ x = - 3 or, - 4 2
⇒ 5y2 + 25y + 2y + 10 = 0
⇒ 5y( y + 5 ) + 2( y + 5 ) = 0
⇒ ( 5y + 2 ) ( y + 5 ) = 0
Hence , required answer will be x = y .∴ y = - 2 or, - 5 5
- Ⅰ. x4 – 227 = 398
Ⅱ. y2 + 321 = 346
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According to question ,we can say that
From equation Ⅰ. x4 = 398 + 227 = 625
From equation Ⅱ. y2 = 346 - 321 = 25Correct Option: E
According to question ,we can say that
From equation Ⅰ. x4 = 398 + 227 = 625
⇒ x4 = 54
From equation Ⅱ. y2 = 346 - 321 = 25
⇒ y2 = 52