Solve the equations {ax + 5Y = 15; 4x-by = - 2

Solve the equations {ax + 5Y = 15; 4x-by = - 2

4aX+20Y=60
4aX-abY=-2a
20Y+abY=60+2a
Y=(60+2a)/(20+ab)
X=[-2+(60b+2ab)/(20+ab)]/4=-1/2+(30b+ab)/(40+2ab)

Given that the two solutions of the equation AX + by = 10 are {x = - 1, y = 0, {x = 1, y = 5, then a =, B=

In fact, it is equivalent to the system of linear equations of two variables about a and B. if they are substituted into the equations, they are all valid
-a+0=10
a+5b=10
a= -10,b=4

A question of filling in the blanks in Grade Seven~
Mother and Tom are sitting__ the table.
A.in B.at C.on D.near
Why are they all different?
……

B.
Sit at the table

Fold the square ABCD so that the vertex a coincides with the point m on the edge of CD. The crease intersects ad at e and BC at F. after the edge AB is folded, it intersects BC at g (as shown in the figure) (1) If the side length of a square is 2, M is the midpoint of the edge of CD. Find the length of EM. (2) if M is the midpoint of the edge of CD, prove de: DM: EM = 3:4:5; (3) if M is any point on the edge of CD, let ab = 2A, ask whether the perimeter of △ CMG is related to the position of point m? If it is relevant, please express the perimeter of △ CMG with the algebraic expression of length x with DM; if it is not relevant, please explain the reason

It is proved that: (1) if De is x, then DM = 1, EM = EA = 2-x, in RT △ DEM, ∠ d = 90 °, de2 + DM2 = em2x2 + 12 = (2-x) 2x = 34,  EM = 54. (2) let the side length of a square be 2, from (1), de = 34, DM = 1, EM = 54, de: DM: EM = 3:4:5; (3) the perimeter of △ CMG has nothing to do with the position of point m. It is proved that if DM = x, de = y, then cm = 2a-x, EM = 2a-y, ∫ EMG = 90 ° and ∧ DME+ The \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\sothe perimeter of △ CMG is 4a, which is the same as that of △ CMG It is independent of the position of point M

Simple calculation of 0.125 × 0.32-0.25 × 0.16

0.125×0.32-0.25×0.16
=0.125×0.32-0.125×2×0.16
=0.125×0.32-0.125×(2×0.16)
=0.125×0.32-0.125×0.32
=0

It's better to give a few more examples,

The weighted average method is to divide the safety evaluation of enterprises into several evaluation tables according to their specialties. All evaluation tables, no matter how many items are evaluated, are evaluated and recorded according to the unified scoring system

On the quadrilateral ABCD, BC is greater than Ba, ad = DC, BD bisector angle ABC, proving angle a + angle B = 180 degrees

It's wrong to prove angle a + angle B = 180 degrees. It should be angle a + angle c = 180 degrees
Proof: intercept be = AB on BC, link De
Because BD bisector angle ABC, BD = BD,
So the triangle abd is equal to the triangle EBD,
So ad = ed, angle a = angle bed,
Because ad = DC,
So Ed = DC,
So angle Dec = angle c,
Because the angle bed + the angle Dec = 180 degrees,
So angle a + angle c = 180 degrees

The mass of China's Long March 3 rocket is 2.43 × 105 kg, and its gravity near the ground is equal to______ In June 1999, China's first practical winged ship was put into operation in Taihu Lake, with a speed of 165 km / h______ M / s

The gravity is g = mg = 2.43 × 105kg × 9.8n/kg = 2.3814 × 106n; 165km / h = 165 × 13.6m/s ≈ 45.83m/s

The calculation problem helps, the intelligence quotient high comes
There are 18 mountains. There are 18 families. There are 18 elder sisters in each family. One elder sister has 18 babies. How many people do you think there are in total

Wow = 18
Home = wow × 18 = 18 × 18 = 324
Elder sister = home × 18 = 324 × 18 = 5832
Baby = big sister × 18 = 5832 × 18 = 104976
Person = baby + elder sister (+ elder sister, their husband) = 104976 + 5832 (+)? = 110808 (+?)
I don't know if I want to count my elder sister's husband. How can I have a baby without a man? Ha ha! I can't say it must be monogamous or anything, so I can't be sure about the number of my elder sister's husbands!
To sum up, if you don't include husbands, there are 110808 people

The perimeter of a rectangle is 130 cm. If its width increases by 15 and its length decreases by 18, a new rectangle with the same perimeter will be obtained. Find the area of the original rectangle

From the meaning of the title: the length of the original rectangle is 130 ／ 2 ／ (8 + 5) × 8 = 40 (CM), the width is 130 ／ 2-40 = 25 (CM), then 25 × 40 = 1000 (square cm); answer: the area of the original rectangle is 1000 square cm