17. Ifa, Bare the zeroes of the polynomial 2-5x + 7. then find a quadratic polynomial whose zeroes are 3a+4b and 4a+3b .
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When roots are given, equation in quadratic form
x
2
−(α+β)x+αβ=0
Here roots are (2α+3β) and (3α+2β)
∴x
2
−(2α+3β+3α+2β)x+(2α+3β)(3α+2β)=0
x
2
−5(α+β)x+6α
2
+4αβ+4αβ+6β
2
=0
f(x)=2x
2
−5x+7
α+β=
2
5
, αβ=
2
7
∴α
2
+β
2
=(α+β)
2
−2αβ
=
4
25
−7=
4
−3
x
2
−5(
2
5
)x+6(−
4
3
)+13×
2
7
=0
∴2x
2
−50x−18+182=0
2x
2
−50x+164=0
∴x
2
−25x+82=0.
x
2
−(α+β)x+αβ=0
Here roots are (2α+3β) and (3α+2β)
∴x
2
−(2α+3β+3α+2β)x+(2α+3β)(3α+2β)=0
x
2
−5(α+β)x+6α
2
+4αβ+4αβ+6β
2
=0
f(x)=2x
2
−5x+7
α+β=
2
5
, αβ=
2
7
∴α
2
+β
2
=(α+β)
2
−2αβ
=
4
25
−7=
4
−3
x
2
−5(
2
5
)x+6(−
4
3
)+13×
2
7
=0
∴2x
2
−50x−18+182=0
2x
2
−50x+164=0
∴x
2
−25x+82=0.
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