Question

Ajutor.Dau coroana.

1.Indica ordinea efectuarii operatiilor,dupa model,si calculeaza.

Model:
25+4×[3+(2×9+16)]=
| | | | |
5 4 3 1 2

(420×5+31)-20×25=
1950-(27×25+40:4)=
39×400+[23+2×(23-2×3)]=
[(470×50-2×190)+70:10×9]-52=

2.Rezolva in doua moduri,filosind propretatile inmultirii:

18×(140+16)=
150×(90-75)=
3×124+3×59=
16×(721-638)=
20×142-20×39

Answer 1

(420×5+31)-20×25=
=(2100+31)-500=
=2131-500=
=1631
ordinea operatiilor: 1 2 4 3

1950-(27×25+40:4)=
=1950-(675+10)=
=1950-685=
=1 265
l l l l
4 1 3 2

39×400+[23+2×(23-2×3)]=
=15 600+[23+2x(23-6)]=
=15 600+(23+2x17)=
=15 600+(23+34)=
=15 600+57=
=15 657
Se fac mai intai operatiile din paranteza rotunda (operatiile de ordinul II (x ,:) si apoi cele de ordinul I (+,-) in ordinea data, apoi cele din paranteza dreapta.
l ll l l l
5 6 4 3 2 1

[(470×50-2×190)+70:10×9]-52=
=[(23 500-380)+7x9]-52=
=(23 120+63)-52=
=23 183-52=
=23 131
l l l l l l l
1 3 2 6 4 5 7

2.Rezolva in doua moduri,filosind propretatile inmultirii:

18×(140+16)=18x156=2 808
18x140+18x16=2 520+288=2 808

150×(90-75)=150x15=2 250
150x90-150x75=13 500-11 250=2 250

3×124+3×59=372+177=549
3x(124+59)=3x183=549

16×(721-638)=16x83=1 328
16x721-16x638=11536-10 208=1 328

20×142-20×39=2 840-780=2 060
20x(142-39)=20x103=2 060