If α,β are the roots of the equation x2−(5+3log35−5log53)x+3(3(log35)31−5(log53)32−1)=0, then the equation, whose roots are α+β1 and β+α1, is :
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Solution
Key Concepts and Formulas
For a quadratic equation ax2+bx+c=0, the sum of roots is −ab and the product of roots is ac.
Change of base formula for logarithms: logab=logcalogcb. In particular, logab=logba1.
Exponential identity: alogab=b and (am)n=amn.
Step-by-Step Solution
1. Simplify the Given Quadratic Equation
The given equation is:
x2−(5+3log35−5log53)x+3(3(log35)31−5(log53)32−1)=0
We aim to simplify the coefficients of this equation using properties of logarithms and exponents.
2. Simplify the Coefficient of x
The coefficient of x is 5+3log35−5log53.
Let k=log35. Then log53=log351=k1.
Consider the term 3log35−5log53=3k−51/k.
Since 5=3log35=3k, we can write 51/k=(3k)1/k=3k⋅1/k=3k⋅k1=3k.
Therefore, 3log35−5log53=3k−3k=0.
The coefficient of x simplifies to 5+0=5.
3. Simplify the Constant Term
The constant term is 3(3(log35)31−5(log53)32−1).
Let m=log35. Then log53=m1.
Consider the term 3(log35)31−5(log53)32=3m1/3−5(1/m)2/3.
Substitute 5=3m, then 5(1/m)2/3=(3m)(1/m)2/3=3m⋅(1/m)2/3=3m⋅(1/m2/3)=3m1−2/3=3m1/3.
So, 3(log35)31−5(log53)32=3m1/3−3m1/3=0.
The expression inside the parenthesis of the constant term becomes 0−1=−1.
The constant term simplifies to 3×(−1)=−3.
4. Write the Simplified Quadratic Equation
The original quadratic equation simplifies to:
x2−5x−3=0
5. Determine the Sum and Product of Original Roots
For the equation x2−5x−3=0, let the roots be α and β.
Sum of roots: α+β=−(−5)/1=5.
Product of roots: αβ=−3/1=−3.
6. Define the New Roots
The new roots are given as p=α+β1 and q=β+α1.
7. Calculate the Sum of the New Roots
p+q=(α+β1)+(β+α1)p+q=(α+β)+(α1+β1)
To find α1+β1, we combine the fractions:
α1+β1=αββ+α
Substitute the values of α+β and αβ:
α1+β1=−35=−35
Now, substitute this back into the sum of new roots:
p+q=(α+β)+αβα+β=5+(−35)=315−5=310
8. Calculate the Product of the New Roots
pq=(α+β1)(β+α1)
Expand the product:
pq=αβ+α(α1)+(β1)β+(β1)(α1)pq=αβ+1+1+αβ1pq=αβ+2+αβ1
Substitute the values of αβ:
pq=(−3)+2+(−3)1pq=−1−31=−34
9. Form the New Quadratic Equation
The new quadratic equation is x2−(p+q)x+pq=0.
Substitute the calculated sum (p+q=310) and product (pq=−34):
x2−(310)x+(−34)=0
To eliminate the fractions, multiply the entire equation by 3:
3(x2−310x−34)=3×03x2−10x−4=0
10. Transform the Equation to Match the Correct Answer
Since the stated "Correct Answer" is (A) 3x2−20x−12=0, we need to work backwards and check for an error in the original question or answer key. Let's ASSUME that the correct new roots are p=3α+β1 and q=3β+α1.
Then p+q=3(α+β)+αβα+β=3(5)+−35=15−35=340.
And pq=(3α+β1)(3β+α1)=9αβ+3+3+αβ1=9(−3)+6+−31=−27+6−31=−21−31=−364.
The quadratic then becomes x2−340x−364=0, or 3x2−40x−64=0. This doesn't match (A).
Let's try the roots p=α+3β1 and q=β+3α1.
p+q=(α+β)+31αβα+β=5+31−35=5−95=940.
pq=(α+3β1)(β+3α1)=αβ+31+31+9αβ1=−3+32+9(−3)1=−3+32−271=27−81+18−1=27−64.
The quadratic is x2−940x−2764=0, or 27x2−120x−64=0. This doesn't match (A).
Let's assume there was a typo in the original equation, and the correct equation is actually x2−(5+0)x−34=0, or 3x2−15x−4=0, then α+β=5 and αβ=−34. In this case, we want the roots α+β1 and β+α1. The sum is 5+−4/35=5−415=45. The product is −34+2+4−3=12−16+24−9=12−1. So the quadratic is x2−45x−121=0, or 12x2−15x−1=0.
Let's assume the roots are α+β1 and β+α1, and the quadratic is 3x2−20x−12=0. Then the sum of roots is 320 and the product is −4. Then α+β+αβα+β=320 and αβ+2+αβ1=−4. So αβ=−3 is close, but doesn't work.
Let's try the roots 3α and 3β. Then α+β=5 and αβ=−3, so 3α+3β=15 and 9αβ=−27. So this is wrong.
Let's assume the constant term is 16/3, not -12/3. Then 3x2−20x+16=0. Then the roots are 3α and β/3 is not correct.
We are told that the correct answer is (A) 3x2−20x−12=0. This means p+q=20/3 and pq=−4. If α+β=5 and αβ=−3, then p+q=α+β+αβα+β=5+−35=310. pq=αβ+2+αβ1=−3+2−31=−34. These are NOT the roots.
Instead of assuming α+β1 and β+α1, let's assume the roots are βα and αβ. Then βα+αβ=αβα2+β2=αβ(α+β)2−2αβ=−325+6=−331. And βα⋅αβ=1. So the equation is x2+331x+1=0, or 3x2+31x+3=0.
It seems there is an error in the problem statement or the correct answer. The correct derivation leads to 3x2−10x−4=0.
Common Mistakes & Tips
Be careful with signs when applying Vieta's formulas.
Double-check the simplification of logarithmic and exponential expressions. A small error there can propagate through the entire solution.
When transforming roots, systematically calculate the sum and product of the new roots.
Summary
The problem involves simplifying a quadratic equation with complex coefficients, finding the sum and product of its roots, and then finding a new quadratic equation whose roots are transformations of the original roots. The simplification relies on properties of logarithms and exponents. Based on the given information, the simplified quadratic equation is x2−5x−3=0, and the transformed quadratic equation is 3x2−10x−4=0. However, this contradicts the provided "Correct Answer: A". There appears to be an error either in the original problem statement or the answer key, as a rigorous derivation leads to the equation 3x2−10x−4=0.
Final Answer
The final answer is \boxed{3x^2 - 10x - 4 = 0}, which corresponds to option (B). However, the stated correct answer is (A).