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a: \(=5^2+16\cdot125-1=24+2000=2024\)
b: \(=-145+55+42-42+90=-90+90=0\)
c: =-4+2+6+8-10+13-15=4+8-10-2=12-10-2=0

Sách Giáo Khoa
Lời giải
a) 15.(-2).(-5).(-6) = [15.(-2)].[(-5)].(-6) = -30.30 = -900 hoặc 15.(-2).(-5).(-6) = [15.(-6)].[(-2).(-5)] = -90.10 = -900 b) 4.7.(-11).(-2) = (4.7).[(-11).(-2)] = 28.22 = 616
a) 15.(-2).(-5).(-6)
= [15.(-2)].[(-5)].(-6)
= -30.30
= -900
hoặc 15.(-2).(-5).(-6)
= [15.(-6)].[(-2).(-5)]
= -90.10
= -900
b) 4.7.(-11).(-2)
= (4.7).[(-11).(-2)]
= 28.22
= 616

a)\(\frac{2}{3}+\frac{3}{4}+\frac{5}{6}\)
\(=\frac{8+9+10}{12}\)
\(=\frac{27}{12}=\frac{9}{4}\)
b)\(\frac{15}{8}-\frac{7}{12}+\frac{5}{6}\)
\(=\frac{45-14+20}{24}\)
\(=\frac{51}{24}=\frac{17}{8}\)
2)
a)\(\frac{2}{5}+\frac{7}{13}+\frac{3}{5}+\frac{1}{7}\)
\(=\frac{2}{5}+\frac{3}{5}+\frac{7}{13}+\frac{1}{7}\)
\(=1+\frac{7}{13}+\frac{1}{7}\)
\(=\frac{20}{13}+\frac{1}{7}\)
\(=\frac{153}{91}\)
Tí tớ trả lời tiếp
b)\(5\frac14+3\frac25-4\frac14\)
=\(\left(5\frac14-4\frac14\right)+3\frac25\)
=\(\left\lbrack\left(5-4\right)+\left(\frac14-\frac14\right)\right\rbrack+\frac{17}{5}\)
=\(1+0+\frac{17}{5}\)
=\(\frac55+\frac{17}{5}\)
=\(\frac{22}{5}\)

B1a)\(11\frac34-\left(6\frac56-4\frac12\right)+1\frac23\)
=\(11\frac34-6\frac56+4\frac12+1\frac23\)
=\(\left(11-6+4+1\right)+\left(\frac34-\frac56+\frac12+\frac23\right)\)
=\(10+\left(\frac{9}{12}-\frac{10}{12}+\frac{6}{12}+\frac{8}{12}\right)\)
=\(10+\left(-\frac{1}{12}+\frac{6}{12}+\frac{8}{12}\right)\)
=10+\(\frac{13}{12}\)
=\(\frac{120}{12}+\frac{13}{12}\)
=\(\frac{133}{12}\)
b)\(2\frac{17}{20}-1\frac{11}{5}+6\frac{9}{20}:3\)
= \(\frac{57}{20}-\frac{16}{5}+\frac{129}{20}\times\frac13\)
=\(\frac{57}{20}-\frac{16}{5}+\frac{129}{60}\)
=\(\frac{171}{60}-\frac{192}{60}+\frac{129}{60}\)
=\(\frac{108}{60}\)
=\(\frac95\)

\(\left(a\right)\frac{8^2.4^5}{2^{20}}=\frac{2^6.2^{10}}{2^{20}}=\frac{2^{16}}{2^{20}}=\frac{1}{2^4}=2^{-4}\)
\(\left(b\right)\frac{90^2}{15^2}=\left(\frac{90}{15}\right)^2=6^2=36\)

\(A=\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\left(\frac{3}{8}+\frac{-6}{8}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\left(\frac{-3}{8}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\left(\frac{-36}{24}+\frac{56}{24}\right):\frac{5}{6}+\frac{1}{2}\)
\(A=\frac{5}{6}:\frac{5}{6}+\frac{1}{2}\)
\(A=\frac{5}{6}\times\frac{6}{5}+\frac{1}{2}\)
\(A=1+\frac{1}{2}\)
\(A=\frac{1}{1}+\frac{1}{2}=\frac{2}{2}+\frac{1}{2}\)
\(A=\frac{3}{2}\)

\(\frac{14.2^5+3.2^6}{2^6}=\frac{2^5\left(14+3.2\right)}{2^6}=\frac{14+6}{2}=\frac{20}{2}=10\)

[ 504 - ( 52 . 8 + 70 ) : 33 + 6 ] : 125
= [ 504 - ( 25 . 8 + 70 ) : 27 + 6 ] : 125
= [ 504 - ( 200 + 70 ) : 27 + 6 ] : 125
= [ 504 - 270 : 27 + 6 ] : 125
= [ 504 - 10 + 6 ] : 125
= 500 : 125
= 4

Ta có:
\(A=\frac{2^{18}.18^7.3^3+3^{15}.2^{15}}{2^{10}.6^{15}+3^{14}.15.4^{13}}=\frac{2^{18}.\left(2.3^2\right)^7.3^3+3^{15}.2^{15}}{2^{10}.\left(2.3\right)^{15}+3^{14}.3.5.\left(2^2\right)^{13}}\)
\(=\frac{2^{18}.2^7.3^{14}.3^3+3^{15}.2^{15}}{2^{10}.2^{15}.3^{15}+3^{15}.5.2^{16}}=\frac{2^{25}.3^{17}+2^{15}.3^{15}}{2^{25}.3^{15}+3^{15}.2^{16}.5}=\frac{2^{15}.3^{15}.\left(3^2.2^{10}+1\right)}{2^{16}.3^{15}.\left(2^9+5\right)}\)
\(=\frac{3^2.2^{10}+1}{2^{10}+10}=\frac{9.1024+1}{1024+10}=\frac{9217}{1025}\)
15 . (–2) . (–5) . (–6)
= [15 . (–2)] . [(–5) . (–6)]
= [– (15.2)] . (5.6)
= (–30) . 30
= –900