bài 2 :
a ) ( – 98 . 36 )
b ) 102 . ( -74 )
bài 3 :
a ) 32. ( – 64 ) . 64 .68
b) -54 . 76 + 16 . ( – 76 )
c) – 12 . 37 – 41 . 12 + 2 . ( -132 )
bài 4 :
a ) 7 . ( 2x – 8 ) = 0
b) (4-x ) . ( x+ 3 ) = 0
c ) – x ( 8 – x ) = 0
d ) ( 3 x – 9 ) . ( 2x – 6 ) = 0
giải đúng nha
`bài 2 : a ) ( – 98 . 36 ) = – ( 98 . 36 ) = -3528`
`b ) 102 . ( -74 ) = – ( 102 . 74 ) = -7548`
bài 3
`a ) 32. ( – 64 ) . 64 .68 = -2048 . 4352 = -8912896`
`b) -54 . 76 + 16 . ( – 76 ) = ( – 54 + 16 ) . [ ( – 76 ) + 16 ] = -38`
`c) – 12 . 37 – 41 . 12 + 2 . ( -132 ) = -444 – 492 + -264 = -1200`
bài 4
`a ) 7 . ( 2x – 8 ) = 0`
` 2x – 8 = 7 : 0 `
`2x – 8 = 0 `
`2x = 0 + 8 `
`2x = 8 `
`x = 8 : 2 `
`x = 4 `
`b) (4-x ) . ( x+ 3 ) = 0`
`4 – x . x + 3 = 0 `
`4 – 2x + 3 = 0 `
`2x + 3 = 4 – 0 `
`2X + 3 = 4 `
`2x = 4 – 3 `
`2x = 1 `
`x = 2 : 1 `
`x = 2 `
`c ) – x ( 8 – x ) = 0`
`-x . 8 – x = 0 `
`-2x . 8 = 0 `
`-2x = 0 : 8 `
`-2x = 0 `
`x = -2 : 0 `
`x= 0 `
`d ) ( 3 x – 9 ) . ( 2x – 6 ) = 0 `
`3x – 9 . 2x – 6 = 0 `
`3 . 2x – 9 . 2 – 6 = 0`
`3 . 2x – 9 . 2 = 0 + 6 `
`3 . 2x – 9 . 2 =6 `
`3.2x – 9 = 6 : 2 = 3`
`3 . 2x = 3 + 9 `
`3 .2x = 12 `
` 2x = 12 : 3 `
`2x = 4 `
`x = 4 : 2 `
`x = 2 `
xin hay nhất
bài 2
a) `(-98.36)`
`=-3528`
b)`102.(-74)`
`=-7548`
bài 3
a)`32.(-64).64.68`
`=-2048.64.68`
`=-131072 .68`
`=-8912896`
b)`-54.76+16.(-76)`
`=-4104+(-1216)`
`=-5320`
c)`-12.37-41.12+2.(-132)`
`=-444-492+(-264)`
`=-936+(-264)`
`=-1200`
bài 4
a)`7.(2x-8)=0`
`2x-8=0:7`
`2x-8=0`
`2x=0+8`
`2x=8`
`x=8:2`
`x=4`
vậy `x=4`
b)`(4-x).(x+3)=0`
`4-2x+3=0`
`2x+3=4-0`
`2x+3=4`
`2x=4-3`
`2x=1`
`x=1:2`
`x=∅`
vậy `x=∅`
c)`-x(8-x)=0`
`-2x.8=0`
`-2x=0:8`
`-2x=0`
`-2x=0:(-2)`
`-2x=0`
vậy `x=0`
d)`(3x-9).(2x-6)=0`
`3.2x-9.2-6=0`
`3.2x-9.2=6`
`3.2x-9=6:2`
`3.2x-9=3`
`3.2x=3+9`
`3.2x=12`
`2x=12:3`
`2x=4`
`x=4:2`
`x=2`
vậy `x=2`