Factorization of the square of a + 5A + B Square of a + 5A + B The square of 2x-x-3 Square of 6x + 7x-5

Factorization of the square of a + 5A + B Square of a + 5A + B The square of 2x-x-3 Square of 6x + 7x-5

Square of a + 5A + B
=a(a+5)+b
The square of 2x-x-3
=(2x-3)(x+1)
Square of 6x + 7x-5
=(2x-1)(3x+5)

A ^ 4-5a ^ 2-36 factorization

Cross multiplication
a^2 +4
a^2 -9
（a^2+4）（a^2-9）=（a^2+4）（a+3）（a-3）

How to write down English words with the scream "ah! And" la! "

If the sequence {Sn / N} constitutes an arithmetic sequence with a tolerance of 2, then A3 =?

The sequence {Sn / N} constitutes an arithmetic sequence with a tolerance of 2,
∴Sn/n=2n,
∴Sn=2n^2,
∴a3=S3-S2=18-8=10.

Let y = y (x) be an implicit function determined by x ^ y = y ^ x, then dy / DX =?

Oh, today, the teacher talked about this problem, dy / DX = negative f (x) / F (y). The second method is to take logarithm in on both sides first, and then seek the derivative of X, where y is y = y (x), so we need to use the derivative rule of composite function!

Three quarters plus two thirds minus five sixths multiplied by 24

3/4+2/3-5/6
=3/4-(5/6-2/3)
=3/4-1/6
=7/12

On whether the volume of the cone is v = π H (R2 + R * r + R2) / 3

Yes
V＝πh(R2＋Rr＋r2)/3
R - upper and lower radius
R - bottom radius
H-high

If a function of two variables is differentiable, then the function must be continuous and the existence of partial derivatives is correct?

Right,
Definition in the book: differentiable, differentiable and continuous
Differentiable is not necessarily differentiable, continuous is not necessarily differentiable
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Do water and ice belong to the same substance?

It's the same substance, because molecules are the smallest particles that keep the properties of objects

Kneel down to seek the formula of cattle eating grass

In addition to summarizing the corresponding solutions to these two types of problems, we should also cultivate the ability to solve practical problems by using the problem-solving ideas of "cattle grazing problem"