Tìm x, y biêt:
a, 3x² – 6x = 0
b, 4y² – 4 = 0
c, x² + 5x + 6 = 0
d, 2x² – 5x – 7 = 0
Tìm x, y biêt: a, 3x² – 6x = 0 b, 4y² – 4 = 0 c, x² + 5x + 6 = 0 d, 2x² – 5x – 7 = 0
By Mackenzie
By Mackenzie
Tìm x, y biêt:
a, 3x² – 6x = 0
b, 4y² – 4 = 0
c, x² + 5x + 6 = 0
d, 2x² – 5x – 7 = 0
Đáp án:
ở dưới
Giải thích các bước giải:
$a)⇔3x.(x-6)=0$
$⇔3x=0$ hay $x-6=0$
$⇔x=0$ hay $x=6$
$b)⇔(2y)^2-2^2=0$
$⇔(2y-2).(2y+2)=0$
$⇔2y-2=0$ hay $2y+2=0$
$⇔y=1$ hay $y=-1$
$c)⇔x^2+2x+3x+6=0$
$⇔x(x+2)+3(x+2)=0$
$⇔(x+2)(x+3)=0$
$⇔x+2=0$ hay $x+3=0$
$⇔x=-2$ hay $x=-3$
$d)⇔2x^2+2x-7x-7=0$
$⇔2x(x+1)-7(x+1)=0$
$⇔(2x-7)(x+1)=0$
$⇔x=7/2,x=1$