\(a,-7-\left[\left(-19\right)+\left(21\right)\right].\left(-3\right)-\left[\left(32\right)+\left(-7\right)\right]\)

\(=-7-\left[21-19\right].\left(-3\right)-\left[32-7\right]\)

\(=-7-2.\left(-3\right)-25\)

\(=-7+6-25=-26\)

\(b,\left(-2\right)^2.3-\left(1^{10}+8\right):\left(-3\right)^2\)

\(=4.3-9:9\)

\(=12-1=11\)

a,\(\left(x-3\right).\left(2y+1\right)=7\)

Vì \(x;y\inℤ=>x-3;2y+1\inℤ\)

\(=>x-3;2y+1\inƯ\left(7\right)\)

Nên ta có bảng sau

Vậy ...

b,\(A=-126-\left(4^2-5\right)^2+870:29\)

\(=-126-\left(16-5\right)^2+30\)

\(=-126-11^2+30\)

\(=-247+30=-217\)

2.
a) (2x + 1)³ = 125
    (2x + 1)³ = 5³
     2x + 1    = 5
     2x          = 5 - 1
     2x          = 4
       x          = 4:2
       x          = 2
Vậy x = 2
b) 5^x+1 = 5⁴
    x + 1 = 4
    x       = 4 - 1 
    x       = 3
Vây x = 3

a) \(A=1.2+2.3+3.4+...+98.99+99.100\)

\(3A=1.2.3+2.3.4+3.4.3+...+99.100.3\) 

\(3A=1.2.\left(3-0\right)+2.3.\left(4-1\right)+3.4.\left(5-2\right)....99.100.\left(101-98\right)\) 

\(3A=\left(1.2.3+2.3.4+3.4.5+...+99.100.101\right)-\left(0.1.2+1.2.3+2.3.4+...+98.99.100\right)\)

\(3A=99.100.101-0.1.2\) 

\(3A=999900-0\)

\(3A=999900\)

\(A=999900:3\)

\(\Rightarrow A=333300\)

\(A=\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6+\frac{7}{4}+\frac{3}{2}\right)\)

\(A=3-\frac{1}{4}+\frac{2}{3}-5+\frac{1}{3}+\frac{6}{5}-6-\frac{7}{4}-\frac{3}{2}\)

\(A=\left(3-5-6\right)-\left(\frac{1}{4}+\frac{7}{4}+\frac{3}{2}\right)+\left(\frac{2}{3}+\frac{1}{3}\right)+\frac{6}{5}\)

\(A=-8-\left(2+\frac{3}{2}\right)+1+\frac{6}{5}\)

\(A=-8-2-\frac{3}{2}+1+\frac{6}{5}\)

\(A=-9-\frac{3}{2}+\frac{6}{5}\)

\(A=\frac{-93}{10}\)

Mk lm đc 1 cách thui

Ủng hộ mk nha ^_-

\(=45-\left(3^2+2^4\right)=45-\left(9+16\right)=45-25=20\)

b)\(=50+\left(30-2\left(14-3\right)\right)=50+\left(30-22\right)=50+8=58\)

\(\frac{1}{2}.\left(\frac{4}{3}+\frac{2}{5}\right)-\frac{3}{4}.\left(\frac{8}{9}+\frac{16}{3}\right)\)

\(=\frac{1}{2}.\left(\frac{20}{15}+\frac{6}{15}\right)-\frac{3}{4}.\left(\frac{8}{9}+\frac{48}{9}\right)\)

\(=\frac{1}{2}.\frac{26}{15}-\frac{3}{4}.\frac{56}{9}\)

\(=\frac{13}{15}-\frac{14}{3}\)

\(=-\frac{19}{5}\)

\(\frac{1}{2}.\left(\frac{4}{3}+\frac{2}{5}\right)-\frac{3}{4}.\left(\frac{8}{9}+\frac{16}{3}\right)\)

\(=\left(\frac{1}{2}.\frac{4}{3}+\frac{1}{2}.\frac{2}{5}\right)-\left(\frac{3}{4}.\frac{8}{9}+\frac{3}{4}.\frac{16}{3}\right)\)

\(=\left(\frac{2}{3}+\frac{1}{5}\right)-\left(\frac{2}{3}+4\right)\)

\(=\frac{2}{3}+\frac{1}{5}-\frac{2}{3}-4\)

\(=\frac{1}{5}-4\)

\(=\frac{1}{5}-\frac{20}{5}=\frac{-19}{5}\)