Solving inequality: 0.5x ^ 2 + 6

Solving inequality: 0.5x ^ 2 + 6

0.5X² + 6 < 4X
0.5X² - 4X + 6 < 0
X² - 8X + 12 < 0
(X - 2)(X - 6) < 0
2 < X < 6
Calculation: the result of 2-2 ^ 2-2 ^ 3 -... - 2 ^ 18-2 ^ 19 + 2 ^ 20 is
2-(2^2 2^3 … 2^19) 2^20=2-[4(1-2^18)/-1] 2^20=2 4-2^20 2^20=6
2-2^2-2^3-2^4-2^5-...-2^19+2^20
=-（2+2^2+2^3+2^4+2^5+...+2^19 ）+4+ 2^20
=Do it yourself
The positional relationship between any real number k, line y = KX + 1 and circle x ^ 2 + y ^ 2 = 2 must be
intersect
The straight line y = KX + 1 must pass through the point (0,1), and the point (0,1) is in the garden, so it intersects
If the rational number XY is such that three of the four numbers x + y, X-Y, XY and X / y are equal, then the value of | y | - | x |
If x + y = X-Y, then y = 0, because y is not equal to 0 in denominator, so x + y = X-Y is not tenable, so different is x + y or X-Y, so xy = x / YXY ^ 2-x = 0x = 0, y = 1, y = - 1, if x = 0, then xy = x / y = 0, then x + y = 0 or X-Y = 0, then all have y = 0, if y = 1, then xy = x / y = x, then x + y = x or X-Y = x, also have y = 0
Solving the system of inequalities 5x-6 ≥ 2x + 6 3x-12 > 4x-12
How to write? I didn't learn
5x-6≥2x+6
5x-2x≥6+6
3x≥12
x≥4
3x-12＞4x-12
4x-3x
Calculation: 2-22-23 - -218-219+220=______ .
Let s = - 22-23 - -218-219, then 2S = - 23 - -218-219-220, 2, 2 - 1, s = - 220 + 4, 2-22-23 - -218-219 + 220 = 2 + S + 220, = 2 + 4-220 + 220, = 6
If two straight lines passing through the fixed point (1, 2) are tangent to the circle x2 + Y2 + KX + 2Y + k2-15 = 0, then the value range of K is ()
A. K ＞ 2B. - 3 ＜ K ＜ 2C. K ＜ - 3 or K ＞ 2D. (− 833, − 3) ∪ (2833)
The equation of the circle is changed into the standard equation, and the result is: (x + 12K) 2 + (y + 1) 2 = 16-34k2, so 16-34k2 > 0, the solution is: - 833 < K < 833, and the point (1, 2) should be outside the known circle, and the point is substituted into the equation of the circle to get: 1 + 4 + K + 4 + k2-15 > 0, that is, (K-2) (K + 3) > 0, the solution is: k > 2 or K < - 3, then the value range of the real number k is (- 833, - 3) ∪ (2833)
If the real number x, y, such that three of the four numbers x + y, X − y, XY, XY are equal, then the value of | y | - | x | is equal to ()
A. −12B. 0C. 12D. 32
So the solution is not equal to y = (X-Y = - 12, X-Y = Y-12)
Known inequality 3 (1-x)
The solution set of inequality is a subset of inequality
Let the solution set of inequality 1 be a and the solution set of inequality be B. then the sentence "all the solution sets of inequality 1 are the solutions of inequality 2" means that a is contained in or equal to B
3x+2/7-2=1-x/3+1
Transfer: 3x + X / 3 = 1 + 1 + 2-2 / 7
Sorting: (10 / 3) x = 26 / 7
The solution is: x = 39 / 35