The square root of any nonnegative number is nonnegative,

The square root of any nonnegative number is nonnegative,

The square root has two numbers, one positive and one negative. For example, the square roots of 4 are - 2 and + 2

If the reciprocal of a negative number a equals itself, then what is the square root of a + 2

If the negative number is - 1, the square root of a + 2 = + 1 or - 1

Given that the shape of parabola y = AX2 and y = 2x2 are the same, then a=______ ．

∵ the shape of parabola y = AX2 is the same as that of y = 2x2, ∵ a | = 2, ∵ a = ± 2

Solving equations x-2y = 0 (1) 3x + 2Y = 8 (2)

x-2y=0(1)
3x+2y=8(2)
(1) + (2) get
4x=8
x=2
Bring in (1)
y=1
therefore
x=2 y=1

(XY ^ 2-2xy + x) times y ^ 3-y / y ^ 3 + y ^ 2

(XY ^ 2-2xy + x) times (y ^ 3-y) (y ^ 3 + y ^ 2)
=x(y^2-2y+1)*[y^2(y+1)]/[y^2(y-1)]
=x(y-1)^2*[y^2(y+1)]/[y^2(y-1)]
=x(y-1)(y+1)

I am a junior one, want to learn quadratic equation of one variable. How to learn?
Be more detailed. It'd better be similar to what the teacher said

We must remember the general solution formula. It can solve any difficult problem
2. Directly make (AX + b) ^ 2 = 0 square root to solve
3. By adding and subtracting constants, we can make (AX + b) ^ 2 = C square root
4. Make (AX + b) * (Cx + D) = 0, let ax + B = 0 --- X1 = A / B, and CX + D = 0 --- x2 = C / d
Where: A, B, C, D are constants, namely Arabic numerals

When x takes what value, the fraction (X-2) (x + 5) (x-3) has meaning; it has no meaning; the value is zero
Hurry, everyone

(x-3)/(x-2)(x+5)
When (X-2) (x + 5) = 0, the fraction is meaningless, that is, when X-2 = 0 or x + 5 = 0, x = 2 or x = - 5, the fraction is meaningless
When (X-2) (x + 5) ≠ 0, the fraction is meaningful, that is, when X-2 ≠ 0 and X + 5 ≠ 0, X ≠ 2 and X ≠ - 5, the fraction is meaningful
When x-3 = 0, the fractional value is 0; when x-3 = 0, x = 3, the fractional value is 0

Home appliances to the countryside is an important measure for China to deal with the current international financial crisis, benefit farmers and strengthen farmers, drive industrial production, promote consumption, and stimulate domestic demand. According to the national regulations, farmers will get 13% of the sales price of home appliances to the countryside. On May 1 this year, a shopping mall sold 20 home appliances to farmers. It is known that the 20 mobile phones sold from a shopping mall were issued by the state If the selling price of the mobile phone is x yuan, the following equation is correct ()
A. 20x•13%=2340B. 20x=2340×13%C. 20x（1-13%）=2340D. 13%•x=2340

If the selling price of mobile phone is x yuan, the subsidy for each mobile phone is 13% X Yuan, and the subsidy for 20 mobile phones is 20x · 13%. Therefore, the equation is: 20x · 13% = 2340

Must the number of equations be greater than or equal to the number of unknowns

When the number of equations is less than the number of unknowns, the specific values of some elements can be solved at most, but not all
For example: x + y + Z = 3, x + y = 2, the value of Z can be solved, but the value of X, y cannot be solved
When the number of equations is greater than the number of unknowns, there may be no solution phenomenon, for example: x + 2Y = 3, x + y = 2, 2x + y = 6
When the number of equations is equal to the number of unknowns, there are generally finite solutions or no solutions
(1) X ^ 2 + X + 1 = 0 (2) 2x + 2Y = 3, x + y = 2 are all cases without solutions

Factorization (1) 4a-6b (2) - 2A ^ 2 + 8ab (3) x ^ 2-5x + 6 (4) x ^ 2-2x-8 (5) 4x ^ 2-9 (6) 49b ^ 2-25a ^ 2 (7) x ^ 2-10x + 25
Please... You don't have to finish it

(1)4a-6b=2（2a-3b）
(2)-2a^2+8ab=-2a（a-4b）
(3)x^2-5x+6=（x-2）（x-3）
( 4)x^2-2x-8 =（x-4)(x+2)
(5)4x^2-9=（2x+3）（2x-3）
(6)49b^2-25a^2=（7b+5a）（7b-5a）
(7)x^2-10x+25=（x-5）²