①x^2+xy-2y^2+2x+7y-3 ②x^2-4xy+3y^2+2x-8y-3 ③x^2+2xy-8y^2+2x+14y-3 Factorization

①x^2+xy-2y^2+2x+7y-3 ②x^2-4xy+3y^2+2x-8y-3 ③x^2+2xy-8y^2+2x+14y-3 Factorization

Decomposition factor: x ^ 2 + 2xy-8y ^ 2 + 2x + 14y-3 analysis: you can use cross multiplication to decompose the quadratic term x ^ 2 + 2xy-8y ^ 2 = (x-2y) (x + 4Y), because the coefficient of Y ^ 2 has been decomposed when decomposing the quadratic term of X, so only the constant term is decomposed this time, and the coefficient of Y is pieced together, Finally, the quadratic trinomial about X is tested. The original formula = (x-2y + 3) (x + 4y-1) Note: the key of double cross multiplication is to decompose the quadratic term about X with cross multiplication, and then decompose the quadratic term about y with cross multiplication (if the coefficient of Y is a complete square, then decompose the quadratic trinomial about x), Finally, we test the quadratic trinomial of X (if we decompose the quadratic trinomial of X for the second time, we test the quadratic trinomial of Y) factorization x ^ 2 + 2xy-8y ^ 2 + 2x + 14y-3, because x ^ 2 + 2xy-8y ^ 2 = (x + 4Y) (x-2y) (x + 4Y) - 1 (x-2y) 3 3 3 (x + 4Y) - 1 (x-2y) = 2x + 14y, so x ^ 2 + 2xy-8y ^ 2 + 2x + 14y-3 = (x + 4y-1) (x-2y + 3) do you understand
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h№xiⅢぬgyh№u〖×ケkⅷu〖×ケcΩ58604868452011-9-11 11:53:40
How to calculate the third order determinant
Multiply three numbers on a solid line to get positive
Multiply the three numbers on the dotted line to get negative
There are 6 terms in total, and the sum of algebras is the value of determinant
Are you in high school or college? There must be in linear algebra
How to solve the equations of 2x + 2-3y + 3 = 10 / 2x + 2 + 7y-7 = 20?
2x-3y=5/2x+7y=25
10y=20
Y=2
x=11/2
By subtracting the two, 10y-10 = 10
Y=2
X=11/2
2x+2-3y+3=10 (1)
2x+2+7y-7=20 (2)
(1) - (2) get
-10y+10=-10
-10y=-20
Y=2
Substituting y = 2 into (1) yields
x=5.5
2X + 2-3y + 3 = 10, 2x = 5 + 3Y can be obtained after the term is shifted. Take this formula into 2x + 2 + 7y-7 = 20 to get 5 + 3Y + 2 + 7y-7 = 20, and then merge to get 10Y = 20 to get y = 2. Because 2x = 5 + 3Y, 2x = 11, x = 5.5, x = 5.5, y = 2
How to calculate the third order determinant
Generally, direct calculation seems troublesome, but in fact, it saves time
Another is to expand by any row or column
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In the solution of the system of equations {x + 7Y = m + 1,2x-y = 4, if the sum of x.y is equal to 1, then what is m
-How did you figure it out
m=-4
x+7y=m+1
2x-y=4
x+y=1
The results are obtained by solving the three equations simultaneously
x=5/3,y=-2/3,m=-4
Direct solution
Type * 2-2 type 15y = 2m-2
Formula 2 * 7 + 15x = m + 29
x+y=1
15(x+y)=15=3m+27
m=-4
Calculation method of third order determinant ～
Solve the equations (1) 2x + 3Y = 12, 2x + y = 0 (2) x + y = 7, 3 (x + y) - 7Y = 7
2x+3y=12 ①
2x+y=0 ②
① The solution is y = 6
By taking y = 6 into 1, 2x + 18 = 12, the solution is x = - 3
x+y=7 ①
3（x+y）-7y=7②
The reduction of 2 to 3x-4y = 7 3
By multiplying 1 by 3 - 3, we get 7Y = 14 and y = 2
Take y = 2 into (1) to get x = 5
(1)x=-3,y=6.(2)x=5,y=2
Finding the sum of all roots of equation [3x + 1] = 2x-1 / 2
{x} Represents the fractional part of X
[x] Represents the integral part of X
Draw a diagram
Solving equations: 2x-3y = 1 4x + 7Y = 5
2x-3y=1 (1)
4x+7y=5 (2)
(2)-2×(1)
7y+6y=5-2
13y=3
therefore
y=3/13
x=(3y+1)/2=11/13
What is the root of the equation 2x-3 = 3x-2?
2x－3＝3x－2
transposition
-1=x
x=-1
－1
_1
-1!