How can the answer be proven correct? 255

You can check online if this answer is correct? Or maybe ask a teacher.

For the correctness of the answer, the result obtained will be brought back, and the result that meets the requirements of the question is the answer to the question (to be sensitive to the data).

Find a teacher, or a classmate, or have the ability to verify it yourself.

If the second condition is used.

z is two decimal places, rounded to see the third place.

For x, 1 decimal place, y is 2 decimal places, for x, 2 decimal places, y is 1 place For x, 3 decimal places, y is an integer.

For the third condition x=z y (x is not roundable), if we follow the above reasoning, divide two decimal places by y, y is 2 decimal places, x is 1 decimal place, ( = 1 -1 = 0

Divide two decimal places by y, y is 1 digit x is 2 decimal places 2--1 = 13 decimal places, and y is an integer 3--1 = 2

In fact, we don't need to deliberately prove that our choices are right or wrong. We just need to stick to what we have in our hearts, and then unswervingly follow the idea, and sooner or later time will tell us the answer.

If the student asks the teacher, he can also look it up on the Internet.

Reverse verify or find its refutation, if you can find it, you are wrong, and if you can't find it, you are wrong.

We look for the right answer from the Internet to prove that the answer is correct.

1) f(-x) =0,-x) f(t)dt, as a variable algebra for t=-y, then dt = dy, Hongsen y = t, then f(-x)= 0,x) f(-y)(-dy) = limb excitation(0,x) -f(y)]dy = 0,x) f(y)dy=f(x), so f(x) is an even function.

2) The same is true.

Just use basic matrix knowledge.

Use the definition of the matrix product.

Let a be an n-order phalanx and the elements in row j of i are aijThe transposition of a is denoted a t, then 0 a 2 a a t

So the main diagonal element of a a t.

a11)^2＋(a12)^2＋.＋a1n)^2＝0(a21)^2＋(a22)^2＋.＋a2n)^2＝0.

an1)^2＋(an2)^2＋.ann) 2 0 so, aij 0, (i, j 1, 2,..n) So, a 0

Because the number series xn is bounded.

Then, there is m>0, and for any n n+, there is |xn|m and lim yn=0,n

Then, for any >0, there is n>0, and when n > n, there is |yn-0|< Then, for the above >0, there is m>0, n>0, and when n > n, there is |xn*yn|Defined by the limit, lim xnyn=0,n

If you don't understand, please ask.

Just use basic matrix knowledge.

Use the definition of the matrix product.

Let a be an n-order phalanx and the elements in row j of i are aijThe transposition of a is denoted a t, then 0 a 2 a a t

So the main diagonal element of a a t.

a11)^2＋(a12)^2＋.＋a1n)^2＝0(a21)^2＋(a22)^2＋.＋a2n)^2＝0

Because m is greater than 0, n+m is greater than n, so when n, n+m, so lim a(n+m)=a

Let t=1-x, then x=1-t

0 x 1, then 0 1-t 1

0 t 1 Replace t with x to get f(x).

The defined domain and image of f(1-x) are exactly the same as those of f(x) f(x) is continuous on [0,1] and is derivable within (0,1), and f(1-x) is continuous on [0,1] and is derivable within (0,1).

Idea: Directly from the image. The images of f(x) and f(1-x) are exactly the same (although the values of the two functions x are different for the same point, the function images are exactly the same).