Tách ít ra thôi bn.

Tách ít ra thôi bn.

a. (83+234)-(34-17)

= (243-34)-(83+17)

= 200-100

= 100

B.(-15)+13+15.(36-25)

= (-15)+15.13+11

= 13+11

= 24

a)

\( 49.(51 - 4) - 51.(49 + 4)\)

\(=49.51-49.4-51.49-51.4\)

\(=49.(51-4-51)-51.4\)

\(=49.(-4)-51.4\)

\(=4.(-49-51)\)

\(=4.(-100)\)

\(=-400\)

b)

\( 71.64 + 32.(-7) - 13.32\)

\(=71.32.2+32.(-7)-13.32\)

\(=142.32+32.(-7)-13.32\)

\(=32.(142-7-13)\)

\(=32.122\)

\(=3904\)

c)

\( 11 + (-13) + 15 + (-17) + ... + 59 + (-61)\)

\(=(-2)+(-2)+...+(-2)\)

\(=(-2).13\)

\(=-26\)

a. 49.51- 49.4 -51.49 -51.4

= -49.4 - 51.4

=4.(-49-51)

=4.-100

=-400

b.71.64 + 32.(-7) -13.32

= 71.64 + 32.(-7-13)

=71.64 + 32.-20 

=71.32.2 +32.-20

=32.(71x2-20)

=32. 122

= 3904

c. (11-13)+(15-17)+..+(59-61)

=-2 x 13

=-26

Bài 2:

a: (x+3)-7=10

=>x+3-7=10

=>x-4=10

=>x=10+4

=>x=14

b: \(2\left(5-x\right)=2^2-2^3\)

=>2(5-x)=4-8=-4

=>5-x=-2

=>x=5+2=7

c: 2x+1 là bội của x-3

=>2x+1⋮x-3

=>2x-6+7⋮x-3

=>7⋮x-3

=>x-3∈{1;-1;7;-7}

=>x∈{4;2;10;-4}

Bài 1:

a: 34-245-234-55

=(34-234)-(245+55)

=-200-300

=-500

b: \(113\cdot39-39-12\cdot39\)

\(=39\left(113-1-12\right)\)

\(=39\cdot100=3900\)

c: \(-200-100:\left\lbrack13-2\left(17-4\cdot5\right)^2\right\rbrack\cdot1^{2021}\)

\(=-200-100:\left\lbrack13-2\left(17-20\right)^2\right\rbrack\)

\(=-200-100:\left\lbrack13-2\cdot3^2\right\rbrack=-200-100:\left(13-18\right)\)

=-200-100:(-5)

=-200+20

=-180

\(P=\dfrac{32}{64}\cdot\dfrac{-57}{19}+\dfrac{35}{21}\cdot\dfrac{22}{44}=\dfrac{1}{2}\left(-3+\dfrac{5}{3}\right)=\dfrac{1}{2}\cdot\dfrac{-4}{3}=\dfrac{-2}{3}\)

\(Q=\dfrac{75}{125}\cdot\dfrac{82}{164}+\dfrac{49}{98}\cdot\dfrac{-35}{105}=\dfrac{1}{2}\left(\dfrac{3}{5}-\dfrac{1}{3}\right)=\dfrac{1}{2}\cdot\dfrac{4}{15}=\dfrac{2}{15}\)

\(46+\left(-80\right)+34=\left(46+34\right)-80=80-80=0\)

\(115-\left(-85\right)+35-\left(46+35\right)=115+85+35-46+35\)

\(=\left(115+85\right)+\left(35-35\right)-46=200+0-46=154\)

\(5\left(-9\right).2.\left(-7\right)\left(-2020\right)^0=\left(-45\right)\left(-14\right).1=630\)

\(57\left(49-16\right)+57\left(24-49\right)=57.49+57.16+57.24-57.49\)

\(=57\left(49-49+16+24\right)=57.40=2280\)