Tìm x biết :
A )3( 2 x -1) – 5 (x-3) + 6(3 x – 4) = 24
B)2 x mũ 2 + 3( x mũ 2 – 1 )= 5 x (x + 1)
C)2 x ( 5 – 3 x) + 2 x (3 x -5) – 3( x – 7) = 3
D) 3 x (x + 1) – 2x (x + 2) = -1 – x
Tìm x biết : A )3( 2 x -1) – 5 (x-3) + 6(3 x – 4) = 24 B)2 x mũ 2 + 3( x mũ 2 – 1 )= 5 x (x + 1) C)2 x ( 5 – 3 x) + 2 x (3 x -5) – 3( x – 7) = 3 D) 3
By Hadley
Đáp án:
`↓↓`
Giải thích các bước giải:
`a) 3(2x-1)-5(x-3)+6(3x-4)=24`
`=> 6x-3-5x+15+18x-24=24`
`=> 19x=24+24-15+3`
`=> 19x=36`
`=> x=36/19`
`b) 2x^2+3(x^2-1)=5x(x+1)`
`=> 2x^2+3x^2-3=5x^2+5x`
`=> 5x^2-5x^2-5x=3`
`=> -5x=3`
`=> x=-3/5`
`c) 2x(5-3x)+2x(3x-5)-3(x-7)=3`
`=> 10x-6x^2+6x^2-10x-3x+21=3`
`=> -3x+21=3`
`=> -3x=-18`
`=> x=6`
`d) 3x(x+1)-2x(x+2)=-1-x`
`=> 3x^2+3x-2x^2-4x=-1-x`
`=> x^2-x=-1-x`
`=> x^2-x+x=-1`
`=> x^2=-1`
`=>` Ko có `x` thỏa mãn
A) 3.(2x-1)-5.(x-3)+6.(3x-4)=24
6x-3-5x+15+18x-24=24
19x=36
x=36/19
B)2 x mũ 2 + 3( x mũ 2 – 1 )= 5 x (x + 1)
2x^2+3x^2-3= 5x^2+5x
2x^2+3x^2-5x^2-5x=3
0x^2-5x=3
-5x=3
x=-3/5
C)2 x ( 5 – 3 x) + 2 x (3 x -5) – 3( x – 7) = 3
10x-6x^2+6x^2-10x-3x+21=3
-3x=-18
x=6
D)3 x (x + 1) – 2x (x + 2) = -1 – x
3x^2+3x-2x^2-4x=-1-x
x^2-x=-1-x
x^2-x+x=1
x^2=1
x=+-1