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If a, b, c are the sides of a triangle h...

If a, b, c are the sides of a triangle having perimeter 2 than the roots of the equation `x^(2)-2sqrt(ab+bc+ca)(x)+abc+1=0` are

A

real and distinct

B

may not be real

C

real but may not be distinct

D

real and equal

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To solve the problem, we need to find the roots of the quadratic equation given by: \[ x^2 - 2\sqrt{ab + bc + ca} \cdot x + (abc + 1) = 0 \] where \( a, b, c \) are the sides of a triangle with a perimeter of 2. ### Step 1: Understand the Perimeter Condition Given that the perimeter of the triangle is 2, we have: \[ a + b + c = 2 \] ### Step 2: Use the Relationship of Sides in a Triangle From the triangle inequality, we know: 1. \( a + b > c \) 2. \( b + c > a \) 3. \( c + a > b \) These inequalities will help us ensure that \( a, b, c \) are valid sides of a triangle. ### Step 3: Calculate \( ab + bc + ca \) Using the identity for the square of the sum: \[ (a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + bc + ca) \] Substituting \( a + b + c = 2 \): \[ 2^2 = a^2 + b^2 + c^2 + 2(ab + bc + ca) \] This simplifies to: \[ 4 = a^2 + b^2 + c^2 + 2(ab + bc + ca) \] Rearranging gives: \[ ab + bc + ca = \frac{4 - (a^2 + b^2 + c^2)}{2} \] ### Step 4: Calculate \( abc \) The product \( abc \) can be expressed in terms of the sides of the triangle. However, without specific values for \( a, b, c \), we cannot simplify it further without loss of generality. ### Step 5: Calculate the Discriminant The discriminant \( D \) of the quadratic equation is given by: \[ D = b^2 - 4ac \] For our equation, substituting \( a = 1 \), \( b = -2\sqrt{ab + bc + ca} \), and \( c = abc + 1 \): \[ D = (-2\sqrt{ab + bc + ca})^2 - 4 \cdot 1 \cdot (abc + 1) \] This simplifies to: \[ D = 4(ab + bc + ca) - 4(abc + 1) \] \[ D = 4(ab + bc + ca - abc - 1) \] ### Step 6: Analyze the Discriminant For the roots to be real and distinct, we need \( D > 0 \): \[ ab + bc + ca - abc - 1 > 0 \] ### Step 7: Conclude the Roots From the analysis, we can conclude that the roots of the equation are real and distinct if the conditions on \( ab + bc + ca \) and \( abc \) hold true. Given that \( a, b, c \) are sides of a triangle, we can assert that the roots will indeed be real and distinct. ### Final Answer Thus, the roots of the equation \( x^2 - 2\sqrt{ab + bc + ca} \cdot x + (abc + 1) = 0 \) are real and distinct.
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FIITJEE-QUADRATIC EQUATION & EXPRESSION -SOLVED PROBLEMS (OBJECTIVE)
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  8. If one root is square of the other root of the equation x^2+p x+q=0 , ...

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  12. If a,b,c are positive rational numbers such that agtbgtc and the quadr...

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  16. If alpha, beta the roots of equation (k + 1 )x ^(2) -(20k +14) x + 91...

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