Question

Решите пожалуйста очень срочно

Answer 1

Ответ:

879. а) 1,7; б) $\frac{1}{{24}};$ в) 3; г) 3,125;

880. а) 2,2; б) 1; в) $\frac{5}{{12}};$ г) 1

Пошаговое объяснение:

Пользуемся формулами ${(a \pm b)^2} = {a^2} \pm 2ab + {b^2}.$

879.

а)

${(x - 6)^2} - x(x + 8) = 2;\\\\{x^2} - 12x + 36 - {x^2} - 8x = 2;\\\\ - 20x = - 34;\\\\x = 1{,}7.$

б)

$9x(x + 6) - {(3x + 1)^2} = 1;\\\\9{x^2} + 54x - 9{x^2} - 6x - 1 = 1;\\\\48x = 2;\\\\x = \displaystyle\frac{1}{{24}}.$

в)

$y(y - 1) - {(y - 5)^2} = 2;\\\\{y^2} - y - {y^2} + 10y - 25 = 2;\\\\9y = 27;\\\\y = 3.$

г)

$16y(2 - y) + {(4y - 5)^2} = 0;\\\\32y - 16{y^2} + 16{y^2} - 40y + 25 = 0;\\\\ - 8y = - 25;\\\\y = \displaystyle\frac{{25}}{8} = 3{,}125.$

880.

а)

${(x - 5)^2} - {x^2} = 3;\\\\{x^2} - 10x + 25 - {x^2} = 3;\\\\ - 10x = - 22;\\\\x = 2{,}2.$

б)

${(2y + 1)^2} - 4{y^2} = 5;\\\\4{y^2} + 4y + 1 - 4{y^2} = 5;\\\\4y = 4;\\\\y = 1.$

в)

$9{x^2} - 1 - {(3x - 2)^2} = 0;\\\\9{x^2} - 1 - 9{x^2} + 12x - 4 = 0;\\\\12x = 5;\\\\x = \displaystyle\frac{5}{{12}}.$

г)

$x + {(5x + 2)^2} = 25(1 + {x^2});\\\\x + 25{x^2} + 20x + 4 = 25 + 25{x^2};\\\\21x = 21;\\\\x = 1.$