9.8×65.2×1.25-12.5×0.652×18．

9.8×65.2×1.25-12.5×0.652×18．

9.8×65.2×1.25-12.5×0.652×18=9.8×65.2×1.25-1.25×65.2×1.8，=65.2×1.25×（9.8-1.8），=65.2×1.25×8，=65.2×（1.25×8）=65.2×10，=652．

18*1/7+3/7*8/13-2/7*9+5/13*3/7
18 × 1 / 7 + 3 / 7 × 8 / 13 - 2 / 7 × 9 + 5 / 13 × 3 / 7

18*1/7+3/7*8/13-2/7*9+5/13*3/7
＝18×1/7＋24/13×1/7－18×1/7＋15/13×1/7
＝﹙18＋24/13－18＋15/13﹚×1/7
＝﹙24/13＋15/13﹚×1/7
＝3×1/7
＝3/7

What is 11 / 5 × (1 / 3-1 / 2) × 3 / 11 △ 4 / 5?

=-11/5*1/6*3/11*5/4
=-1/8

If 5 + 3 = 28,9 + 1 = 810.8 + 6 = 214,5 + 4 = 19,7 + 3 =?

410
First, subtract the two numbers and put them in the front, then add them and put them in the back

Known: 1 = 5, 2 = 7, 3 = 11, 4 = 19, ask 5 =? Intelligence problem

5 = 1, because the first equation: 1 = 5

Solve a system of equations ········· x + y + Z = 49x + 3Y + Z = 144x-2y + Z = 19 as long as the result!

X=2
Y=-3
Z=5

Solving equations 4 / x + 3 / 2Y = - 1 2 (x + y) - 3 (X-Y) = - 19

Is the first equation: 4 / x + 3 / 2Y = - 1
{4/x+3/2y=-1
{2(x+y)-3(x-y)=-19
The results are as follows
{3x+8y=-12 1）
{x-5y=19 2）
1) - 2) × 3
8y+15y=-12-57
y=-3
Substituting into formula 2, we get the following result:
x=4
{x=4,y=-3

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Skillfully calculate 19 + 9 + 1 / 2 + 7 + 1 / 4 + 3 + 1 / 8 + 8 + 1 / 16

Solution: integer part add, fraction part add, 1 / 2 + 1 / 4 + 1 / 8 + 1 / 16 tell you a rule, in the denominator is 2 into the 1 th power, 2 th power, 3 th power, 4 th power, 5 th power. N power arrangement, the sum of the sequence is 2 of the n th power - 1 / 2 of the n th power / represents the fractional line, this can be used as theorem 19 + 9 and 1 / 2 + 7 and 1 / 4