Find the value of the polynomial 5x square - (3Y square + 5x Square) + (4Y square + 7xy), where x = - 1, y = 3

Find the value of the polynomial 5x square - (3Y square + 5x Square) + (4Y square + 7xy), where x = - 1, y = 3

Original formula = 5x square - 3Y square - 5x square + 4Y square + 7xy
=Y squared + 7xy
=9-21
=-12
How to find the - 2 power of (1 / 3)?
Original formula = 3 ^ 2 = 9
＝(3^(-1))^(-2)
= 3^(-1*-2)
= 3^2
= 9
The solution of inequality (A-2) X2 - (a2-2a + 3) x + 3A > 0 about X
If a = 2, X ＞ - 2
After the emergence of the fourth power, did not judge its positive and negative
We know the equation (M + 2) x2-5mx + M-3 = 0 about X. (1) prove that the equation has real roots; (2) if the equation has two real roots and the sum of two squares is equal to 3, find the value of M
(1) It is proved that: when m + 2 = 0, the equation is changed to 25x-5 = 0, and the solution is x = 52; when m + 2 ≠ 0, △ = (- 5m) 2-4 (M + 2) (M-3) = (M + 2) 2 + 20, ∵ (M + 2) 2 ≥ 0, ∵ △ 0, that is, when m ≠ - 2, the equation has two unequal real roots, and the equation has real roots
Find the power set of the following sets: (1) empty set; (2) {empty set}; (3) {empty set, {empty set}}
The so-called power set is a set family composed of all subsets (including complete set and empty set) in the original set
(1) Empty set
(2) Empty set, {empty set}
(3) Empty set, {empty set}, {empty set}, {empty set, {empty set}}
The solution set of inequality X2 - (2a + 1) x + A2 + a less than 0 is a, the solution set of inequality x2-5x + 4 greater than or equal to 0 is B, a and B = B, and the range of a is obtained
x²-(2a+1)x+a²+a
On the two real roots of the equation x & # 178; - MX + m + 5 = 0 are α and β, and the two real roots of the equation x & # 178; - (8m + 1) x + 15m + 7 = 0 are α and γ, find the value of α & # 178; β γ + 11?
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If the number of elements of set a is 10, then the number of elements of its power set is ()
Mainly explain the ideas and methods
If the number of elements of set a is 10, then the number of elements of its power set is (2 ^ 10)
　　　　1+C(10,1)+C(10,2)+… +C(10,10) = 2^10.
This conclusion is found in the textbook. Turn to the book
If the solution set of the inequality system x2 + 2x-3 is greater than or equal to 0 and x2-a2 is less than 0, then the value range of the real number a is empty
（x+3)(x-1)>=0
X=1
x²
If the equation mx2-mx + 2 = 0 about X has two equal real roots, then M=______ .
∵ the equation mx2-mx + 2 = 0 of X has two equal real roots, ∵ △ = (- M) 2-4 × 2m = 0, and m ≠ 0, the solution is m = 8; so the answer is: 8