If the 2nd and 5th terms of a
1 answer:
Answer:
45
Step-by-step explanation:
The n th term of a GP is
= a
where a is the first term and r the common ratio
Given a₂ = 6 and a₅ = 48, then
ar = 6 → (1)
a = 48 → (2)
Divide (2) by (1)
=
, that is
r³ = 8 ( take the cube root of both sides )
r = = 2
Substitute r = 2 into (1)
2a = 6 ( divide both sides by 2 )
a = 3
Thus
3, 6, 12, 24 ← are the first 4 terms
3 + 6 + 12 + 24 = 45 ← sum of first 4 terms
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Answer:
P(x) = - 7x² + 12
Step-by-step explanation:
Given zeros x = 2, x = - 2, x = , x = -
Then the factors are (x - 2), (x + 2), (x - ), (x +
)
and the polynomial is the product of the factors, that is
P(x) = (x - 2)(x + 2)(x - )(x +
) ← expand in pairs using FOIL
= (x² - 4)(x² - 3) ← distribute
= - 3x² - 4x² + 12 ← collect like terms
= - 7x² + 12