The given quadratic equation is 3x2+5x−1=0.
Let α and β be the roots of this equation.
For a quadratic equation ax2+bx+c=0, the sum of the roots is α+β=−ab and the product of the roots is αβ=ac.
From 3x2+5x−1=0, we have a=3, b=5, c=−1.
The sum of the roots is:
α+β=−35
The product of the roots is:
αβ=3−1
To construct a new quadratic equation with roots r1 and r2, the general form is x2−(r1+r2)x+r1r2=0.
a) Roots are 5α,5β
Step 1: Calculate the sum of the new roots.
S′=5α+5β=5(α+β)=5(−35)=−325
Step 2: Calculate the product of the new roots.
P′=(5α)(5β)=25αβ=25(−31)=−325
Step 3: Form the new quadratic equation.
x2−S′x+P′=0
x2−(−325)x+(−325)=0
x2+325x−325=0
Multiply by 3 to clear the denominators:
3x2+25x−25=0
b) Roots are α2,β2
Step 1: Calculate the sum of the new roots.
S′=α2+β2=(α+β)2−2αβ
S′=(−35)2−2(−31)=925+32=925+96=931
Step 2: Calculate the product of the new roots.
P′=α2β2=(αβ)2=(−31)2=91
Step 3: Form the new quadratic equation.
x2−S′x+P′=0
x2−931x+91=0
Multiply by 9 to clear the denominators:
9x2−31x+1=0
c) Roots are α1,β1
Step 1: Calculate the sum of the new roots.
S′=α1+β1=αββ+α
S′=−31−35=5
Step 2: Calculate the product of the new roots.
P′=(α1)(β1)=αβ1
P′=−311=−3
Step 3: Form the new quadratic equation.
x2−S′x+P′=0
x2−5x−3=0
x2−5x−3=0
d) Roots are α+β1,β+α1
Step 1: Calculate the sum of the new roots.
S′=(α+β1)+(β+α1)=(α+β)+(α1+β1)
We know α+β=−35 and α1+β1=αβα+β=−31−35=5.
S′=−35+5=−35+315=310
Step 2: Calculate the product of the new roots.
P′=(α+β1)(β+α1)=αβ+α(α1)+(β1)β+(β1)(α1)
P′=αβ+1+1+αβ1=αβ+2+αβ1
P′=(−31)+2+−311=−31+2−3
P′=−31−1=−31−33=−34
Step 3: Form the new quadratic equation.
x2−S′x+P′=0
x2−310x−34=0
Multiply by 3 to clear the denominators:
3x2−10x−4=0
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