Tìm x, biết: a, 2x(3x+5)-x(6x-1)=33 b, (x+1)(x+3)-x(x+2=7 c,(3x-5)(2x-1)-(x+2)(6x-1)=0 d, (x-2) ³-(x+5)(x ²-5x+25)+6x ²=11

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1. $a,2x(3x+5)-x(6x-1)=33$

   $⇒6x² +10x -6x²+1=33$

   $⇒10x+1=33$

   $⇒10x=32$

   $⇒x=3,2$

   $b, (x+1)(x+3)-x(x+2)=7$

   $⇒x²+3x+x+3-x²-2x=7$

   $⇒2x=10$ $⇒x=5$

   $c,(3x-5)(2x-1)-(x+2)(6x-1)=0$

   $⇒6x²-3x-10x+5-( 6x² -x+12x-2 )=0$

   $⇒6x²-3x-10x+5- 6x² +x-12x+2 =0$

   $⇒-24x=-7$ $⇒x=7/24$

   $d, (x-2) ³-(x+5)(x ²-5x+25)+6x ²=11$

   $⇒x³- 6x²+12x-8-(x³-5x²+25x+5x²-25x+125)+6x²=11$

   $⇒x³- 6x²+12x-8-x³+5x²-25x-5x²+25x-125+6x²=11$

   $⇒12x=11+133$

   $⇒x=12$

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2. Đáp án:

    

   Giải thích các bước giải:

   a,2x(3x+5)-x(6x-1)=33

   ⇒6x² +10x -6x²+1=33

   ⇒10x+1=33

   ⇒10x=32

   ⇒x=3.2

   b, (x+1)(x+3)-x(x+2)=7

   ⇒x²+3x+x+3-x²-2x=7

   ⇒2x=10

   ⇒x=5

   c,(3x-5)(2x-1)-(x+2)(6x-1)=0

   ⇒6x²-3x-10x+5-( 6x² -x+12x-2 )=0

   ⇒6x²-3x-10x+5- 6x² +x-12x+2 =0

   ⇒-24x=-7

   ⇒x=7/24

   d, (x-2) ³-(x+5)(x ²-5x+25)+6x ²=11

   ⇒x³- 6x²+12x-8-(x³-5x²+25x+5x²-25x+125)+6x²=11

   ⇒x³- 6x²+12x-8-x³+5x²-25x-5x²+25x-125+6x²=11

   ⇒12x=11+133

   ⇒12x=144

   ⇒x=12

   Chúc em học tốt nhé ( Good lucky )

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