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a ) x = − 3 4 + 4 5 ⇔ x = 1 20 b ) x = − 4 9 : 2 , 5 ⇔ x = − 8 45 c ) 3 , 5 − 2 x = 1 7 : 2 3 7 ⇔ 3 , 5 − 2 x = 1 17 ⇔ 2 x = 3 , 5 − 1 17 ⇔ 2 x = 117 34 ⇔ x = 117 34 : 2 = 117 68
125-(30+x+125)=(x-237).[8+(-237)]
125-(30+x+125)=(x-237)×(-229)
125-(30+x+125)=x-237×(-229)
125-(30+x+125)=x-(-54273)
125-(30+x+125)=x+54273
125-30+x+125=x+54273
125-39+x=x+54273-125
125-39+x=x+54148
125-x=x+54148-39
125-x=x+54109
125-1x=1x+54109
125-1x=0
1x=125-0
1x=125
x=125÷1
x=125
Bài giải
Ta có: \(\frac{49+\left(-49\right).\left(-2\right)}{7.21}\)
= \(\frac{49.1+49.2}{7.21}\)
= \(\frac{49.\left(1+2\right)}{7.21}\)
= \(\frac{49.3}{7.21}\)
= \(\frac{7.7.3}{7.7.3}\)
= \(1\)
\(a,\left(13+150+47\right)-\left(13+47\right)\)
\(=13+150+47-13-47\)
\(=\left[13+\left(-13\right)\right]+\left[47+\left(-47\right)\right]+150\)
\(=0+0+150\)
\(=150\)
\(b,\left(-237\right)-\left[\left(-237+155\right)-55\right]\)
\(=\left(-237\right)+237+155-55\)
\(=0+100\)
\(=100\)
\(c,57.\left(62-43\right)-62.\left(57-43\right)\)
\(=57.62-57.43-62.57+62.43\)
\(=-57.43+62.43\)
\(=43.\left(-57+62\right)\)
\(=43.5\)
\(=215\)
a , ( 13 + 150 + 47 ) - ( 13 + 47 )
= 12 + 150 + 47 - 13 - 47
= [ 12 + ( - 13 ) ] + [ 47 + ( - 47 ) ] + 150
= - 1 + 0 + 150
= 149
b , ( - 237 ) - [ ( - 237 + 155 ) - 55 ]
= - 237 - [ - 237 + 155 - 55 ]
= - 237 + 237 - 155 + 55
= [ ( - 237 ) + 237 ] + [ ( - 155 ) + 55 ]
= 0 + ( - 100 )
= - 100
c , 57 . ( 62 - 43 ) - 62 . ( 57 - 43 )
= 57 . 62 - 57 . 43 - 62 . 57 - 62 . 43
= [ 57 . 62 - 62 . 57 ] . [ 62 . 43 - 62 . 43 ]
= 0 . 0
= 0
bằng 21 nha bn
yick mk nha
237 + ( 49 - 237 ) - ( 49 - 21 )
= 237 + 49 - 237 - 49 + 21
= ( 237 - 237 ) + ( 49 - 49 ) + 21
= 0 + 0 + 21
= 21