C] [ X-1/2 ] CHIA [ 1/2 CONG 1/6 CONG 1/12 CONG 1/20 ] = 1/3
A] X-1,25x4= 2,5 b] [ X CONG 1 ] CONG [ X CONG 2] CONG [ X CONG 3 CONG ] .............. CONG [ X CONG 20] = 750 C ] [ X CONG 1] CONG [X CONG 2 ] CONG [ X CONG 3 ] CONG ........... CONG [ X CONG 10] = 175
a) Ta có: X-1,25x4= 2,5
=)X-1,25= 2,5:4= 0,625
=)X= 0,625+1,25= 1,875
Vậy X= 1,875
b) Ta có: (X+1)+(X+2)+(X+3)+...+(X+20) = 750
=)X+1+X+2+X+3+...+X+20(20 chữ số X) = 750
=)20X+(1+2+3+...+20) = 750
=)20X+[(1+20)+(2+19)+...+(10+11)] = 750 (10 cặp số hạng)
=)20X+(21+21+21+...+21) = 750
=)20X+21x10 = 750
=)20X+210 = 750
=)20X = 750-210 = 540
=)X = 540:20 = 27
Vậy X = 27
Câu C bạn nhìn phần B rồi tự nghĩ nha. Luời quá rồi
o 1 nha may co 3 to cong nhan neu lay 20% so cong nhan o to 1 chia deu cho 2 to con lai tyhi so cong nhan o 3 to bang nhau neu to 1 co them 8 cong nhan thi so cong nhan cua to 1 bang tong so cong nhan cua 2 to kia hoi to 1 co ? cong nhan
ta có tất cả số công nhân là:
20x2x8=218
đáp số:218
1phan 2 cong 1phan 6 cong 1 phan 12 cong 1phan 20 cong 1phan 30 cong mot phan 42 cong mot phan 56 cong mot phan 72 =????
[ X 1 cong ] cong [ X 2 cong ] cong[ X3 cong] CONG .............. CONG 20 = 750
??????????????????????????????????????????????????????????????????????????????????????????????????????????????
b ơi b vt đề rõ hẳn ra đc k vt như b khó hiểu quá
cmr A=1 cong 5 cong 5 mu 2 cong 5 mu 3 cong ....cong 5 mu 21 chia het cho 6
tim z,y,z thoa
can x cong can tat ca y tru 1 cong can tat ca z tru 2 bang 1 phan 2 ( x cong y cong z)
tim GTN cua B bang 1 phan x tru can x cong 1
tim x thuoc z de can x cong 1 phan can 3 tru 3 la so nguyen
tinh tong T bang 1 phan can 1 cong can 2 cong 1 phan can 2 cong can 3 cong ... cong den 1 phan can 99 cong can 100
tìm x < x cong 4/6> cong 3/4 - 1/2 =2 va 1/3
( x + 4/6 ) + 3/4 - 1/2 = 7/3
⇒ ( x + 4/6 ) + 1/4 = 7/3
⇒ x + 4/6 = 25/12
⇒ x = 17/12.
Vậy x = 17/12.
chung to rang B = 1/2mu 2 cong 1/3 mu 2 cong 1/4 mu 2 cong 1/5 mu 2 cong 1/6 mu 2cong 1/7 mu 2 cong 1/8 mu2 nho hon 1
1 CONG 3 CONG 5 CONG .........CONG [ 2 x X CONG 1] = 169
ai tra loi giup mk voi