Question

найти a1 и d если а1*а11=14        а2+а10=24
20 баллоооов

Answer 1

$a_{1}* a_{11} =14$
$a_{2} + a_{10} =24$

$a_{1} *( a_{1} +10d)=14$
$a_{1} +d+( a_{1} +9d)=24$

$(a_{1} )^2+10d*a_{1} =14$
$2 a_{1} +10d=24$

$10d=24-2 a_{1}$
$a_{1}( a_{1} +24-2 a_{1} ) =14$

$(a_{1})^2-24 a_{1} +14=0$
D=576-56=520
$a_{1} =12+2 \sqrt{130}$
$a_{1} =12-2 \sqrt[n]{130}$