Question

вычислить: а) 8/9*3/4-(5/6-1/4) б)3/5+4/5*3/7+6/7 в)(2/5-2/7):2/7*2/5
г)(5/6-3/10):(3/10+2/15)

Answer 1

вычислить:

а) 8/9*3/4-(5/6-1/4) = 1/12.

1)) (5/6- 1/4)= (5•2)/(6•2)- (1•3)/(4•3)= 10/12 - 3/12= 7/12;
2)) 8/9•3/4= 2/3• 1/1= 2/3;
{сократили, значит поделили 8 и 4 на 4; 9 и 3 на 3};
3)) 2/3 - 7/12= (2•4)/(3•4) - 7/12= 8/12- 7/12= 1/12;


б)3/5+4/5*3/7+6/7 = 1целая 4/5.

1)) 4/5• 3/7= 12/35;
2)) 3/5+ 12/35+ 6/7= (3•7)/(5•7) + 12/35+ (6•5)/(7•5)= 21/35 + 12/35 + 30/35= 63/35= 1 целая 28/35= 1 целая 4/5.
{сократили 28/35 на 7}.



в)(2/5-2/7):2/7*2/5= 4/25.

1)) (2/5- 2/7)= (2•7)/(5•7) - (2•5)/(7•5)= 14/35 - 10/35= 4/35;
2)) 4/35 : 2/7= 4/35• 7/2= 2/5• 1/1= 2/5;
{сократили 4 и 2 на 2; 35 и 7 на 7};
3)) 2/5• 2/5= 4/25;



г)(5/6-3/10):(3/10+2/15)= 1целая 3/13.

1)) (5/6-3/10)= (5•5)/(6•5) - (3•3)/(10•3)= 25/30 - 9/30= 16/30;
2)) (3/10+ 2/15)= (3•3)/(10•3) + (2•2)/(15•2)= 9/30+ 4/30= 13/30;
3)) 16/30 : 13/30= 16/30• 30/13= 16/13= 1целая 3/13;
{сократили 30 и 30 на 30}.