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`a)` `2/5 + 3/5 xx 4/9 - 1/3`
`= 2/5 + 4/15 - 1/3`
`= 6/15 + 4/15 - 5/15`
`= 1/3`
`b)` `( 5/2 - 1/3 ) xx 9/2 - 1/2`
`= ( 15/6 - 2/6 ) xx 9/2 - 1/2`
`= 13/6 xx 9/2 - 1/2`
`= 39/4 - 2/4`
`= 37/4`
\(\dfrac{1}{5}\times\dfrac{4}{7}+\dfrac{3}{7}\times\dfrac{1}{5}-\dfrac{1}{5}\)
\(=\dfrac{4}{35}+\dfrac{3}{35}-\dfrac{1}{5}\)
\(=\dfrac{7}{35}-\dfrac{1}{5}\)
\(=\dfrac{1}{5}-\dfrac{1}{5}\)
\(=0\)
a) \(\left|x\right|+2=2^3.\left(-2\right)^2\)
\(\Leftrightarrow\)\(\left|x\right|+2=32\)
\(\Leftrightarrow\)\(\left|x\right|=30\)
\(\Leftrightarrow\)\(x=\pm30\)
Vậy...
b) \(\left|x\right|+4=\left(-3\right)^2+\left(-2\right)\)
\(\Leftrightarrow\)\(\left|x\right|+4=7\)
\(\Leftrightarrow\)\(\left|x\right|=3\)
\(\Leftrightarrow\)\(x=\pm10\)
Vậy...
b2 :
a) 5 . ( -5 - 6 )
= 5 . ( -11 )
= -55
b) 321 + { - 15 + [ 30 + ( -321 ) ] }
= 321 + { - 15 + [ - 291 ] }
= 321 + ( - 306 )
= 15
19 . 92 - 9 . ( - 19 ) - 19
= 1748 - ( -171 ) - 19
= 1919 - 19
= 1900
1.a) 168 - 300 : 15
= 168 - 20 = 148
b) 103 - 13 = 90
2. 87 - (321 - x) = 75 : 5 = 15
321 - x = 87 - 15
321 - x = 72
x = 321 - 72 = 249
\(1-\frac{1}{2}+1+1.2\)
\(=\frac{1}{2}+1+2\)
\(=\frac{1}{2}+3=3\frac{1}{2}\)
a: =>(2x-1)^5=2^5
=>2x-1=2
=>2x=3
=>x=3/2
b: =>3^x=243*27=3^5*3^3=3^8
=>x=8
\(321+587.32=321+18784=19105\)
\(\frac{1}{2}+\frac{1}{5}.\frac{4}{5}=\frac{1}{2}+\frac{4}{25}=\frac{33}{50}\)
321+587*32
=321+18784
=19105
1/2+1/5*4/5
=1/2+4/25
=33/50
tick nha các bạn