task/30046639 x² - 2a(x -1) -1 =0 ; x₁ +x₂ =x₁² +x₂² ; a - ?
решение x² - 2a(x -1) -1 = 0 ⇔x² - 2ax +2a -1 =0
x₁ +x₂ =x₁² +x₂²⇔ x₁ +x₂ =(x₁ +x₂)² - 2x₁*x₂ || x₁ +x₂ =2a ; x*x₂=2a -1 т.Виета ||
2a =(2a)²- 2(2a -1) ⇔ 2a=4a²- 4a + 2 =0 ⇔ 4a²- 6a + 2 =0 ⇔2a²-3a +1 =0 ⇔
[ a = 1 ; a = 1/2 .
ответ: 0,5 ; 1 .
task/30046639 x² - 2a(x -1) -1 =0 ; x₁ +x₂ =x₁² +x₂² ; a - ?
решение x² - 2a(x -1) -1 = 0 ⇔x² - 2ax +2a -1 =0
x₁ +x₂ =x₁² +x₂²⇔ x₁ +x₂ =(x₁ +x₂)² - 2x₁*x₂ || x₁ +x₂ =2a ; x*x₂=2a -1 т.Виета ||
2a =(2a)²- 2(2a -1) ⇔ 2a=4a²- 4a + 2 =0 ⇔ 4a²- 6a + 2 =0 ⇔2a²-3a +1 =0 ⇔
[ a = 1 ; a = 1/2 .
ответ: 0,5 ; 1 .