32/3x7+6/7x41+9/41x10+1/10.51+19/51x14
tính hợp lí:
32/3.7 + 6/7.41 + 9/41.10 + 1/ 10.51 + 19/51.14
nhanh hộ mik vs ạ, ai làm nhanh mà đúng thì mik tick cho, cảm ơn
A = 4 / 7x31 + 6 / 7x41 +9 / 10 x41 + 7 / 10 x57
B = 7 / 19 x 31 + 5 / 19 x 43 + 3 / 23 x43 + 11 / 23 x 57
A = 4 / 7x31 + 6 / 7x41 +9 / 10 x41 + 7 / 10 x57
B = 7 / 19 x 31 + 5 / 19 x 43 + 3 / 23 x43 + 11 / 23 x 57
A/B = ????
A=4/7x31+6/7x41+9/10x41+7/10x57
B=7/19X31+5/19/43X3/23X43+11/23X57
Tính A/B
tinh nhanh 4/7x3+6/7x41+9/10x41+7/10x57
A=\(\dfrac{4}{7x31}\)+\(\dfrac{6}{7x41}\)+\(\dfrac{9}{10x41}\)+\(\dfrac{7}{10x57}\)
\(A=\dfrac{20}{35\cdot31}+\dfrac{30}{35\cdot41}+\dfrac{45}{41\cdot50}+\dfrac{35}{50\cdot57}\)
=5(4/31*35+6/35*41+9/41*50+7/50*57)
=5(1/31-1/35+1/35-1/41+1/41-1/50+1/50-1/57)
=5*(1/31-1/57)
=130/1767
5/57 x x = 4/7x31 + 6/7x41 + 9/10x41 + 7/10x57
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