Step 1: Identify coefficients for the quadratic equation 5x2+21x−20=0.
The standard form is ax2+bx+c=0.
Here, a=5, b=21, c=−20.
a) Find α+β
The sum of the roots of a quadratic equation is given by α+β=−ab.
α+β=−521
The sum of the roots is −521.
b) Find αβ
The product of the roots of a quadratic equation is given by αβ=ac.
αβ=5−20=−4
The product of the roots is −4.
c) Find α2+β2
We use the identity α2+β2=(α+β)2−2αβ.
Substitute the values from parts (a) and (b):
α2+β2=(−521)2−2(−4)
α2+β2=25441+8
α2+β2=25441+258×25
α2+β2=25441+25200
α2+β2=25641
The value of α2+β2 is 25641.
d) Find α3+β3
We use the identity α3+β3=(α+β)3−3αβ(α+β).
Substitute the values from parts (a) and (b):
α3+β3=(−521)3−3(−4)(−521)
α3+β3=−1259261−12(521)
α3+β3=−1259261−5252
To combine these, find a common denominator, which is 125:
α3+β3=−1259261−125252×25
α3+β3=−1259261−1256300
α3+β3=−12515561
The value of α3+β3 is −12515561.
e) Find α1+β1
Combine the fractions:
α1+β1=αββ+α
Substitute the values from parts (a) and (b):
α1+β1=−4−521
α1+β1=521×41
α1+β1=2021
The value of α1+β1 is 2021.
f) Find α21+β21
Combine the fractions:
α21+β21=(αβ)2β2+α2
Substitute the values from parts (b) and (c):
α21+β21=(−4)225641
α21+β21=1625641