dam dat co chieu dong la 60m, chieu dai bang 4phan3 la chieu rong, do do

60 . 4phan3 = 80m

nguoi ta danh 7phan12 dien tich de trong cay,do do dien tich dat de trong cay la

7phan12 . 4800 = 7. 4800phan12 = 2800m vuong

dap an: dien tich ao ca la 600met vuong 

tu so: A = n-

Mau so: B = n-2

phan so M = AphanB la toi gian neu va chi neu UOC SO CHUNG LON NHAT (UCLN) CUA A VA B BANG 1 , tuc la:

(n - 1,n-2) = 1

ta co 

(n - 1)-(n - 2) = 1

(a,b)+ (b,a - b)

vi UCLN (N - 1, N-2) = 1 nen phan so M = n - 1 phan n - 2  L APHAN SO TOI GIAN

DAP AN:

 vay M la phan so toi gian. DIEU PHAI CHUNG MINH 

quan sat hinh ve, ta co cac bo ba diem thang hang sau

A,E,F

B,E,D

C,E,F

theo de bai, doan AB = 9 cm va I la diem nam giua  A va B sao c ho AI = 4 cm

vi I NAM GIUA DIEM A VA B , nen ta co : 

AB = AI + IB

9 = 4 + IB 

suy ra IB = 9-4 = 5 cm

dap an cau 1: cac bo ba diem thang hang la (A,E,F)(B,E,D)(C,E,F)

cau 2a : IB = 5 cm

b: tu cau a, ta da tim duoc IB = 5cm 

vi E LA TRUNG DIEM CUA IB, nen ta co:

AE = AI = IBphan2

dap an: do dai doan AE = 6,5 cm

MSC: 495

-5phan9 = -275phan495, 8phan15 = 264phan495

-275phan495 + 8phan5 -90phan495 +231phan495

rut gon phan so 

350phan495 = 10phan15 = 2phan3

dap an cau A: 2phan3

cau B

QDMSC: 6

5phan2 = 15phan6, 2phan6 = 2phan6

7. 13phan6 = 91phan6

7phan6 - 2phan7 

QDMSC: 42

7phan6 = 49phan42, 2phan7 = 12phan42

7 : 37phan42 = 7. 42phan37= 7.42phan37 = 294phan37

91phan6 + 6

6 = 36phan6

dap an : 127phan6

-3 phan 8 > 5 phan -12

571+216+129+124

(571+129)+(216+124)

=646+340=986

27.74+26.27-355

=27.74=1998, 26.27=702

=(1998+702)-355

=2435

100:{250:(450-[500-4.25)]}

=100:{250:[450-(12400)

=100:{250:[450-12400]}

=100:{250:11950}

100:47.8

=2

số 320,4914,90 chia hết cho 2

số 320,2 315,90 chia hết cho 5

số 320,2 315,90,543 chia hết cho 3

số 320,90 chia hết cho cả 2,3,5,9.