-3/26.(-15/19)-2/19.-3/26
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\(d,-\dfrac{3}{26}.\left(-\dfrac{15}{19}\right)+\dfrac{2}{19}.\left(-\dfrac{3}{26}\right)\\=-\dfrac{3}{26}.\left(-\dfrac{15}{19}+\dfrac{2}{19}\right)\\ =-\dfrac{13}{19}.\left(-\dfrac{3}{26}\right)\\ =\dfrac{3}{38}. \)
d) \(\dfrac{-3}{26}\times\left(\dfrac{-15}{19}\right)+\dfrac{2}{19}\times\dfrac{-3}{26}\)
\(=\dfrac{-3}{26}\times\left[\left(\dfrac{-15}{19}\right)+\dfrac{2}{19}\right]\)
\(=\dfrac{-3}{26}\times\dfrac{-13}{19}\)
\(=\dfrac{3}{38}\)
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`@` `\text {Ans}`
`\downarrow`
Lớp 6 - 8 phải k ạ? Lớp 5 chưa học dạng ntnay.
\(15 . ( x- 3 ) + 3 (x+ 26 ) = 19 . ( x + 1)\)
`=>`\(15x-45+3x+78=19x+19\)
`=> 15x - 45 + 3x + 78 - 19x - 19 = 0`
`=> (15x + 3x - 19x) + (-45 + 78 - 19) = 0`
`=> -x + 14 = 0`
`=> -x = -14`
`=> x = 14`
Vậy, `x = 14.`
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\(B=\dfrac{7.2^{10}.3^{10}2.^{21}.3^6-2^{19}.2^{15}.3^{15}}{3^2.2^{15}.3^{15}.2^{13}-2^2.3^{15}.2^{26}}=\)
\(=\dfrac{2^{31}.3^{15}\left(7.3-2^3\right)}{2^{28}.3^{15}\left(3^2-1\right)}=\dfrac{2^{31}.13}{2^{31}}=13\)
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= (26/15-7/15):19/45
=\(\dfrac{19}{15}:\dfrac{19}{45}\)
=\(\dfrac{19}{15}x\dfrac{45}{19}=\dfrac{45}{15}=3\)
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\(B=\frac{7.6^{10}.2^{20}.3^6-2^{19}.6^{15}}{9.6^{19}.2^9-4.3^{17}.2^{26}}\)
\(B=\frac{7.\left(2.3\right)^{10}.2^{20}.3^6-2^{19}.\left(2.3\right)^{15}}{3^2.\left(2.3\right)^{19}.2^9-2^2.3^{17}.2^{26}}\)
\(B=\frac{7.2^{30}.3^{16}-2^{34}.3^{15}}{3^{21}.2^{11}-2^{28}.3^{17}}\)
\(B=\frac{2^{30}.3^{15}.\left(7.3-2^4\right)}{3^{17}.2^{11}.\left(3^4-2^{17}\right)}\)
\(B=\frac{2^{19}.\left(21-2^4\right)}{3^2.\left(3^4-2^{17}\right)}\)
@_@ tự tính!
\(B=\frac{7.\left(2.3\right)^{10}.2^{20}.3^6-2^{19}.\left(2.3\right)^{15}}{3^2.\left(2.3\right)^{19}.2^9-4.3^{17}.2^{26}}\\ B=\frac{7.2^{10}.3^{10}.2^{20}.3^6-2^{19}.2^{15}.3^{15}}{3^2.2^{19}.3^{19}.2^9-2^2.3^{17}.2^{26}}\\ B=\frac{7.2^{30}.3^{16}-2^{34}.3^{15}}{3^{21}.2^{28}-2^{28}.3^{17}}\)
\(B=\frac{7.2^{30}.3.3^{15}-2^{34}.3^{15}}{3^{15}.3^6.2^{28}-2^{28}.3^{15}.3^2}\\ B=\frac{3^{15}.\left(7.2^{30}.3-3^{34}\right)}{3^{15}.\cdot\left(3^6-3^2\right)}\\ B=\frac{7.2^{30}.3-3^{34}}{3^6-3^2}\)
=-3/26(-15/29-2/19)
=-3/26*(-17/19)
=3/26*17/19
=51/494
\(-\dfrac{3}{26}.\left(-\dfrac{15}{19}\right)-\dfrac{2}{19}.\left(-\dfrac{3}{26}\right)\)
\(=-\dfrac{3}{26}.\text{[}\left(-\dfrac{15}{19}-\dfrac{2}{19}\right)\)
\(=-\dfrac{3}{26}.\left(-\dfrac{17}{19}\right)\)
=\(\dfrac{51}{494}\)