Tìm x,biết a) 3( x + 1) + 4( x-2 ) = 7 b) 2( 3x -2 ) – 5 ( x+1) =10 c) 2x ( x+1 ) -2( x + 3 ) = 5 d) 3x ( x-2 )+ x ( 5 – 3x )= 10

0 bình luận về “Tìm x,biết a) 3( x + 1) + 4( x-2 ) = 7 b) 2( 3x -2 ) – 5 ( x+1) =10 c) 2x ( x+1 ) -2( x + 3 ) = 5 d) 3x ( x-2 )+ x ( 5 – 3x )= 10”

1. $\text{Đáp án+Giải thích các bước giải:}$

   $\text{a) 3(x+1)+4(x-2)=7}$

   $\text{⇔ 3x+3+4x-8=7}$

   $\text{⇔ 7x-5=7}$

   $\text{⇔ 7x=12}$

   $\text{⇔ x=$\frac{12}{7}$}$

   $\text{b) 6x-4-5x-5=10}$

   $\text{⇔ x-9=10}$

   $\text{⇔ x=19}$

   $\text{c) 2x²+2x-2x-6=5}$

   $\text{⇔ 2x²=11}$

   $\text{⇔ x²=$\frac{11}{2}$}$ 

   $\text{⇔ x=±√$\frac{11}{2}$}$

   $\text{d) 3x²-6x+5x-3x²=10}$

   $\text{⇔ -x=10}$

   $\text{⇔ x=-10}$

   Bình luận

2. `#DyHungg`

   `a) 3(x+1)+4(x-2)=7`

   `⇔3x+3+4x-8=7`

   `⇔7x=-3+8+7`

   `⇔7x=12`

   `⇔x=12/7`

   Vậy `S={12/7}`

   ……………..

   `b) 2(3x-2)-5(x+1)=10`

   `⇔6x-4-5x-5=10`

   `⇔6x-5x=4+5+10`

   `⇔x=19`

   Vậy `S={19}`

   ……………

   `c) 2x(x+1)-2(x+3)=5`

   `⇔2x²+2x-2x-6=5`

   `⇔2x²=6+5`

   `⇔2x²=11`

   `⇔x²=11/2`

   `⇔x=±\sqrt{11/2}`

   Vậy `S={±\sqrt{11/2}}`

   ………………..

   `d) 3x(x-2)+x(5-3x)=10`

   `⇔3x^2-6x+5x-3x^2=10`

   `⇔-x=10`

   `⇔x=-10`

   Vậy `S={-10}`

    

   Bình luận