Toán Lớp 10: Giai cac pt sau:
|x^2 -3x+2| = x+2
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Toán Lớp 10: Giai cac pt sau:
|x^2 -3x+2| = x+2
Comments ( 1 )
Với x + 2 \ge 0 <=> x \ge -2
(1) => x^2 -3x + 2 = x + 2
<=> x^2 -3x – x + 2 -2 = 0
<=> x^2 -4x = 0
<=>$\left[\begin{matrix} x=4(Nhận)\\ x=0(Nhận )\end{matrix}\right.$
Với x + 2 < 0 <=> x < -2
(1) => x^2 – 3x + 2 = ( x+ 2)^2
<=> x^2 – 3x + 2 = x^2 + 4x + 4
<=> x^2 – x^2 -3x -7x = 4 – 2
<=> -10x = 2
<=> x = \frac{-2}{10} (Loại)
Vậy phương trình có nghiệm x = 4 ; x = 0