Mohon bantuannya yaaa (soal um).... Question from @Has17

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$\displaystyle x_1^2+x_2^2=(x_1+x_2)^2-2x_1x_2\\x_1^2+x_2^2=\left(-\frac ba\right)^2-\frac{2c}{a}\\x_1^2+x_2^2=\left(-\frac{a-2}1\right)^2-\frac{2(-a)}{1}\\x_1^2+x_2^2=a^2-4a+4+2a\\x_1^2+x_2^2=a^2-2a+4\\\text{karena minimum maka }\\a=-\frac{-2}{2(1)}\\a=1\\\\12(x_1+x_2-x_1x_2)=12\left(-\frac ba-\frac ca\right)\\12(x_1+x_2-x_1x_2)=12\left(-\frac{1-2}1-\frac{-1}1\right)\\12(x_1+x_2-x_1x_2)=12(1+1)\\12(x_1+x_2-x_1x_2)=24\\\\x_1^2+x_2^2=a^2-2a+4\\x_1^2+x_2^2=1^2-2(1)+4\\x_1^2+x_2^2=1-2+4\\x_1^2+x_2^2=3$

$\displaystyle u_2=12(x_1+x_2-x_1x_2)\\ar=24\\\\u_5=x_1^2+x_2^2\\ar^4=3\\ar\cdot r^3=3\\24r^3=3\\r^3=\frac18\\r=\frac12\\\\ar=24\\a\cdot\frac12=24\\\boxed{\boxed{a=48}}$

1 votes Thanks 1

arsetpopeye

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X^2 + (a - 2)x - a = 0
x1^2 + x2^2 ==> minimum
= (x1 + x2)^2 - 2x1.x2
= (-(a - 2)/1)^2 - 2 (-a)/1
= a^2 - 4a + 4 + 2a
= a^2 - 2a + 4
Kita cari titik stasioner nya agar nilainya minimum dg turunan pertama
=> 2a - 2 = 0
=> 2a = 2
=> a = 1
x^2 + (a - 2)x - a = 0
x^2 + (1 - 2)x - 1 = 0
x^2 - x - 1 = 0
x1 + x2 = -(-1)/1 = 1
x1.x2 = c/a = -1/1 = -1
Barisan geometri
U2 = 12(x1 + x2 - x1.x2) = 12(1 - (-1)) = 12(2) = 24
U5 = x1^2 + x2^2 = (x1 + x2)^2 - 2x1.x2 = 1^2 - 2(-1) = 1 + 2 = 3

U5/U2 = 3/24
(ar^4)/(ar) = 1/8
r^3 = (1/2)^3
r = 1/2

U2 = 24
ar = 24
a(1/2) = 24
a = 48 => suku pertama

0 votes Thanks 1

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No 5 gimana ya caranya?

Itu gimana ya caranya?

Yang no 11 gimana ya?

Itu gimana ya? Mohon bantuannya

Cuales son los efectos del calentamiento global que afectan el lugar donde vives, por favor.

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