Question

помогите решить
заранее спасибо!

Answer 1

$left { {{b_5+b_3=60} atop {b_7-b_5=144}} right. ; left { {{b_1q^4+b_1q^2=60} atop {b_1q^6-b_1q^4=144}} right. ; left { {{b_1q^2(q^2+1)=60} atop {b_1q^4(q^2-1)=144}} right. \\ frac{b_1q^4(q^2-1)}{b_1q^2(q^2+1)}= frac{144}{60}\\q^2(q^2-1)=2,4(q^2+1)\\q^4-q^2=2,4q^2+2,4\\q^4-3,4q^2-2,4=0; |cdot 5\\5q^4-17q^2-12=0; ; to ; ; t=q^2; ,; ; 5t^2-17t-12=0\\D=529; ,; ; t_1= frac{17-23}{10}=- frac{3}{5}; ,; t_2=frac{17+23}{10}=4\\q^2=-frac{3}{5} textless 0; ; net; kornej$

$q^2=4; ; ; to ; ; ; q=pm 2\\ b_1q^2(q^2+1)=60; ; to ; ; b_1cdot 4cdot 5=60; ,; b_1=3\\b_2=b_1q=pm 3cdot 2=pm 6\\b_4=b_1q^3=pm 3cdot 8=pm 24\\b_2cdot b_4=(pm 6)cdot (pm 24)=+144$