Tìm X biết:

a) 2×(3X-1)×(2X+5)-6×(2X-1)×(X+2)=-6

b) (2X+3)×(X-4)+(X-5)×(X-2)=(3X-5)×(X-4)
Giúp mình với!

Question

Tìm X biết:

a) 2×(3X-1)×(2X+5)-6×(2X-1)×(X+2)=-6

b) (2X+3)×(X-4)+(X-5)×(X-2)=(3X-5)×(X-4)
Giúp mình với!

Ninh Hoàng · Accepted Answer

a)

$$2\left(3x-1\right)\left(2x+5\right)-6\left(2x-1\right)\left(x+2\right)=-6$$

$$2\left(6x^2+13x-5\right)-6\left(2x^2+3x-2\right)=-6$$

$$12x^2+26x-10-12x^2-18x+12+6=0$$

$$8x+8=0$$

$$8x=-8$$

$$x=-1$$

Vậy x = -1.

b)

$$\left(2x+3\right)\left(x-4\right)+\left(x-5\right)\left(x-2\right)=\left(3x-5\right)\left(x-4\right)$$

$$2x^2-5x-12+x^2-7x+10=3x^2-17x+20$$

$$3x^2-12x-2=3x^2-17x+20$$

$$\left(3x^2-3x^2\right)+\left(-12x+17x\right)=20+2$$

$$5x=22$$

$$x=\frac{22}{5}$$

Vậy $$x=\frac{22}{5}$$.

Timi · Answer

a) 2×(3X-1)×(2X+5)-6×(2X-1)×(X+2)=-6

Ta có:
2×(3X-1)×(2X+5)-6×(2X-1)×(X+2)=-6
= 2×(3X-1)×(2X+5)-3×2×(2X-1)×(X+2)=-6
= 2×(3X-1)×(2X+5)-2×(3×2X-3)×(X+2)=-6
= 2×(3X-1)×(2X+5)-2×(6X-3)×(X+2)=-6
= 2×(3X-1)×(2X+5)-2×(3X-1)×2×(X+2)=-6
= 2×(3X-1)×[(2X+5)-2×(X+2)] = -6
= 2×(3X-1)×(2X+5-2X-4) = -6
= 2×(3X-1)×1 = -6
= 2×(3X-1) = -6
= 3X-1 = -3
= 3X = -2
= X = $\frac{-2}{3}$
Vậy X = $\frac{-2}{3}$

b) (2X+3)×(X-4)+(X-5)×(X-2)=(3X-5)×(X-4)

Ta có:
(2X+3)×(X-4)+(X-5)×(X-2)=(3X-5)×(X-4)
= (2X+3)×(X-4)-(3X-5)×(X-4)+(X-5)×(X-2)=0
= (X-4)×[(2X+3)-(3X-5)]+(X-5)×(X-2)=0
= (X-4)×(-X+8)+(X-5)×(X-2)=0
= -X²+8X+4X-32+X²-2X-5X+10=0
= 5X-22=0
= 5X=22
= X=$\frac{22}{5}$
Vậy X=$\frac{22}{5}$

Tìm X biết: a) 2×(3X-1)×(2X+5)-6×(2X-1)×(X+2)=-6 b) (2X+3)×(X-4)+(X-5)×(X-2)=(3X-5)×(X-4) Giúp mình với!