Move a matchstick so that 31-17 = 65 + 8 holds

Move a matchstick so that 31-17 = 65 + 8 holds

Move "-" to "=" and it becomes 3117 ≠ 65 + 8. Because the title does not say that the title is an equality, it can be turned into an inequality

1 + 11 + 111 = 14 move a matchstick and let the formula hold

1+11+1+1=14

What is 1024 + 1024?

2G

Finding the derivative of piecewise function
The original topic is on page 57 of Li Yongle's Review Book 2010 Edition (last year). I also found a similar topic in Chen Wendeng's review guide, but there is no explanation. There is a piecewise function f (x): = SiNx, X is less than or equal to the quarter group; = ax + B, X is greater than the quarter group. Try to determine the value of constant a, B, When I do this, I directly use the left and right derivations to get the value of a at the quarter of the dividing point. Then I know that the function must be continuous at the dividing point according to the theorem that the derivability must be continuous. Why do I use the definition of continuity to get the value of B at the dividing point? Can't b take any value, Because I think that as long as a determines that the function can be differentiable, it must be continuous. Why do you need to find it continuous to get the value of B? It feels contradictory, like the continuous function must be continuous at the dividing point. Is the theorem that differentiable must be continuous useless?

Of course, it's useful to be continuous
Derivable must be continuous, that is, discontinuous must not be derivable
So in the title, if it is derivable, we must first satisfy the continuity
So B can not take any value, otherwise it is not necessarily continuous
It may not be able to lead, so it is not the meaning of the problem

A simple algorithm of 3333 * 3334 + 2222 * 9999

3333×3334+2222×9999
=3333×3334+2222×3×3333
=3333×（3334+6666）
=3333×10000
=33330000

Compare two fifths of three fifths, three fifths of two fifths, two fifths of two fifths

Two fifths of three fifths < two fifths of two fifths < three fifths of two fifths

Do not change the value of fraction 2x of 3 + 2x of Y - 5Y of 2, and change the coefficients in the numerator denominator into integers

1×1／2＋2×1/3＋3×1/4＋4×1/5＋5×1/6＋…… 98×1/99＋99×1/100

Original formula = 1 / 2 + 2 / 3 + 3 / 4 + +98/99+99/100
=(1-1/2)+(1-1/3)+(1-1/4)+…… +(1-1/99)+(1-1/100)
=100-1/2-1/3-1/4-…… -1/99-1/100
……

The square of a rational number must be a negative number, B positive number, C non negative number, D non positive number

C is nonnegative

If 6x + a = 12 and 3x + 1 = 6 have the same solution, then a=

6x+a=12
6x=12-a
x=(12-a)/6
3x+1=6
3x=5
x=5/3
So (12-A) / 6 = 5 / 3
Double six on both sides
12-a=10
a=2