Tìm x, y biết : a)5×3 – 3×2 + 10x – 6 = 0
b)X2 + y2 – 2x + 4y + 5 = 0
Tìm x, y biết : a)5×3 – 3×2 + 10x – 6 = 0 b)X2 + y2 – 2x + 4y + 5 = 0
By Madelyn
By Madelyn
Tìm x, y biết : a)5×3 – 3×2 + 10x – 6 = 0
b)X2 + y2 – 2x + 4y + 5 = 0
$a) 5x³ – 3x² + 10x – 6 = 0$
$x²(5x – 3) + 2(5x – 3) = 0$
$(x² + 2)(5x – 3) = 0$
$x² + 2 = 0 //hoặc// 5x – 3 = 0$
$x² + 2 > 0 5x = 3$
$=> Vô lí x = 3/5$
$//Vậy// x = 3/5$
b) $x² + y² – 2x + 4y + 5 = 0$
$x² – 2x + 1 + y² + 4y + 4 = 0$
$(x – 1)² + (y + 2)² = 0$
$(x – 1)² = 0 //và// (y + 2)² = 0$
$x – 1 = 0 y + 2 = 0$
$x = 1 y = – 2$
$//Vậy// x = 1; y = – 2$
Học tốt nhé!