HOC24
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Ta có : \(VT = ( x^{2} - xy -y ) . (x +y) + xy (y + 1) \)
= \(x^{3} + x^{2}y - x^{2}y = xy^{2} -xy - y^{2} + xy^{2} + xy\)
= \(x^{3} - y^{2} = VP\)
\(\Leftrightarrow \left[\begin{array}{} x+3 = 0\\ 2x + 2 = 0 \end{array} \right. \Leftrightarrow\left[\begin{array}{} x = -3\\ x= -1 \end{array} \right.\)
Ta có:
( 3x + 1). ( 2x- 3) - 6x. (x + 2) = 16
3x ( 2x -3)+ 1.(2x – 3 ) - 6x. x – 6x . 2 = 16
6x^2 – 9x + 2x – 3 – 6x^2 - 12x = 16
-19x = 16 + 3
- 19x = 19
x = - 1
4(18 - 5x) - 12(3x - 7) = 15(2x - 16) - 6(x + 14)
⇔ 4.18 - 4.5x - 12.3x - 12.(-7) = 15.2x - 15.16 - 6x - 6.14
⇔ 72 - 20x - 36x + 84 = 30x - 240 - 6x - 84
⇔ 156 - 56x = 24x - 324
⇔ 56x + 24x = 156 + 324
⇔ 80x = 480 ⇔ x = 6
2(x+3) + 4(2-2x) = 2(x-2)
2x + 6 +8 - *x = 2x-4
-6x + 14 = 2x -4
-6x -2x = -4 -14
-8x = -18
x = 18/8 = 9/4
(x+3) . (x+5) = (x+4) . (2 +x)
\(x^{2} + 3x + 5x + 15 = x^{2} + 4x + 2x + 8\)
\(x^{2} + 3x + 5x + 15 - x^{2} - 4x _ 2x - 8 =0\)
2x + 7 = 0
2x = -7
x= -7 : 2
x = -7/2
(x-1) . (2x -3) - 2x^{2} = 0
2x^{2} - 3x - 2x + 3 - 2x^{2} = 0
-5x +3 = 0
-5x= -3
x= \dfrac{3}{5}
x/7 + x/2 = x/14 + 3/14
=> 2x/14 + 7x/14 = x/4 + 3/14
=> 2x + 7x = x+3
=> 9x = x+3
=> 9x - x =3
=> 8x = 3
=> x = 3/8
a)
-3/35 = -1/35 - 2/35
-1/35 + ( -2/35) = -3/35
b)
-3/35 = 2/35 - 5/35
2/35 - 5/35 = -3/35
c)
-3/35 = -3/7 . 1/5
-3/7 . 1/5 = -3/35
d)
-3/35 = 6/5 : (-7/7)
6/5 : (-7/7) = -3/35