The new operation * is defined as a * b = (1 / a multiplied by 1 / b) finding 3 * (4 * 5)

The new operation * is defined as a * b = (1 / a multiplied by 1 / b) finding 3 * (4 * 5)

4*5=1/4×1/5=1/20
So the original formula is 3 * 1 / 20
=1/3×1/（1/20）
=1/3×20
=20/3

Define a new operation: a △ B = a × B - (a + b) find: (3 △ 4) △ 5

(3△4)△5
=[3x4-(3+4)]△5
=(12-7)△5
=5△5
=5x5-(5+5)
=25-10
=15

Define a new operation with}: for any rational number a, B, there is a} B = | - a | - (- b) |, then what is the value of 5} (- 3)

A:
Set 5 and - 3 together
5★(-3)=|5|-|-(-(-3))|=|5|-|-(3)|=5-3=2
In fact, no matter how many minus signs there are in the absolute value, the absolute value of the number will be the final value. If we see this rule, then we can see that
5-3 = 5-3 = 2 in one step

*It means a * b = negative a multiplied by B negative (a + b) to find (1) 3 * 5 (2) (negative 3) * (negative 5)
What is the formula

1 -3*5*-（3+5）= -15*-8=120
2 3*-5*-(-3-5)=-15*8=-120

*A * b = the sum of negative a multiplied by B minus a plus B. find (1) 3 * 5 (2) (- 3) * - 5

（1）3*5
=（-3）×5-（3+5）
=-15-8
=-23
（2）（-3）*（-5）
=3×（-5）-（-3-5）
=-15+8
=-7

If there are 8 numbers, every 4 numbers are one group, how many groups are there? What is the calculation method?

It's very simple
Adding eight numbers is the label of 1 2 3 4 5 6 7 8
For label 1, it needs to choose three of the remaining seven as teammates to form a group. The remaining four are a group
So the answer is c73, 7 * 6 * 5 / (1 * 2 * 3) and the answer is 35 points

How can 1 / 2, 1 / 4, 1 / 8 and 1 / 16 be equal to 8
How to calculate 1 / 2, 1 / 4, 1 / 8 and 1 / 16 equal to 8 needs to be calculated in order.

1/2/(1/4-1/8-1/16)

12 △ 3 = 4 and 12 △ 4 = 3 have the same meaning, right or wrong

Wrong
The first one means to divide 12 into 3 parts, each 4
The second means to divide 12 into 4 parts, 3 for each

Do 5 × 4 and 4 × 5 have the same meaning?

In the current teaching, we often encounter such problems. For now, I think such problems can only be judged in the specific environment. Because the four five and five four are right. The examiner who gives such problems is too poor!

- 8-3 + 1-7, read according to the meaning of "he": read according to the meaning of "operation":

- 8-3 + 1-7, read as the sum of - 8, - 3, + 1 and - 7
Read in the sense of "operation" - 8 minus 3 plus 1 minus 7