if α and β are the roots of the equation 2x^2-12x+3=0,then 3/α^2 +3/β^2=
a.4/3
b.44
c.48
d.33
if f(x)=3x^2+6x-1 and f(a)=f(b)=0 then a^2/b+b^2/a=
a.13.5
b.17
c.30
d.24.5
f4 maths αβ questions
2012-05-12 8:13 pm
回答 (1)
2012-05-12 8:20 pm
✔ 最佳答案
1 α + β = 6, αβ = 3/23/α^2 +3/β^2
= 3(α^2 + β^2)/(αβ)^2
= 3[6^2 - 2(3/2)]/(3/2)^2
= 3 * 33 * 4/9
= 44 (B)
2 a + b = -2, ab = -1/3
a^2/b + b^2/a
= (a^3 + b^)/ab
= [(a + b)^3 - 3ab(a + b)]/ab
= [-8 - 3(-1/3)(-2)]/(-1/3)
= 30 (C)
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