1. There are 40 pieces of RMB 10 yuan and 5 yuan, with a total currency value of 325 yuan. How many pieces of RMB 10 yuan and 5 yuan?

1. There are 40 pieces of RMB 10 yuan and 5 yuan, with a total currency value of 325 yuan. How many pieces of RMB 10 yuan and 5 yuan?

Interesting question, 25 times 10, 250, 15 times 5, 75, 250 and 75, 325

3. There are 15 pieces of RMB 5 yuan and 10 yuan, 100 yuan in total. How many pieces of RMB 5 yuan and 10 yuan?

This is the problem of chicken and rabbit in the same cage. We just finished last semester
Suppose it's all five yuan
5x15 = 75 yuan
100-75 = 25 yuan
10 yuan: 25 / (10-5) = 5 (sheets)
5 yuan: 15-5 = 10 (sheets)

AB is the diameter of the circle O, C is a point on the circle O, ad and the tangent passing through C are vertical, and the perpendicular foot is D. the AC bisector angle DAB is proved

Connect to OC
OC vertical DC, ad vertical DC
So OC parallels ad
Angle OCA = DAC
In the isosceles triangle OAC
Angle OCA = OAC
So OAC = DAC
AC bisector DAB

If the line (3m-n) x + (M + 2n) y-n = 0 passes through a certain point P, what is the coordinate of P?
Big brother, big sister, help (to process)

In this kind of problem, put aside the one with X and put aside the one with y. then make the left and right zeros of the equal sign OK
Think for yourself

In rectangular paper ABCD, ab = 3cm, BC = 4cm. Now fold and flatten the paper so that a and C coincide. If the crease is EF, the area of the overlapping part △ AEF is equal to______ ．

Let AE = x, from folding, EC = x, be = 4-x, in RT △ Abe, AB2 + be2 = AE2, that is 32 + (4-x) 2 = X2, the solution is: x = 258, from folding, we can know ∠ AEF = ∠ CEF, ∫ ad ‖ BC, ∫ CEF = ∠ AFE, ∫ AEF = ∠ AFE, that is AE = AF = 258, ∫ s △ AEF = 12 × AF × AB = 12 × 258 × 3 = 7516

The function f (x) = - x ^ 2 + m is known, where m is a constant. Verification: the function is a decreasing function on R. when the function is an odd function, the value of the real number m is obtained

Certification:
(1) There are two real numbers in the definition field of function f (x): A, B, and 0

4.6 + 3 / 5 2 + 6 / 5 3 + 5.4

"It's very simple, first calculate 4.6 + 5.4 = 10, then calculate 3 and 5 / 2 + 6 and 5 / 3 or equal to 10, and the result will be 10 + 10 = 20

It is known that when factoring the polynomial 6x ^ 2 + 5x-k, there is a factor 3x-2 to find another factor and the value of K

Let another factor be a, then 6x & # 178; + 5x-k = a (3x-2) x = 2 / 3, 3x-2 = 0, so the right side equals 0, so the left side equals 0, so x = 2 / 36x & # 178; + 5x-k = 8 / 3 + 10 / 3-K = 0, so k = 66x & # 178; + 5x-6 = 6x & # 178; - 4x + 9x-6 = 2x (3x-2) + 3 (3x-2) = (3x-2) (2x + 3), so another factor is 2x

Distance from vertex a of cube abcd-a1b1c1d1 with edge length a to section b1cd

First of all, the plane of b1cd is the same as b1cda1, then the diagonal a1d of rectangle a1add1 is on one side of rectangle b1cda1, then the distance is half Ao of diagonal AD1, then Ao is equal to 2 / 2 root sign 2 times a, the general idea is like this, you can straighten the process again. Ah! I'm so tired! Give me the share!

What is the one digit number of 4 to the power of 1999

=4^1998 *4
=16 ^ 999 * 4, multiplying 16 by 6, the number of bits is always the same
The number of bits is the same as 6 * 4 = 4