It is known that the real number range of a for a set a = {x | x square-2x-8 less than 0} B = {x | x less than a} a intersection B = a

It is known that the real number range of a for a set a = {x | x square-2x-8 less than 0} B = {x | x less than a} a intersection B = a

According to the condition a = {x | x square - 2x-8 is less than 0}, we can get the following results:
A={x|x∈（-2,4）}.
A intersects B = a, that is to say, a is contained in B
So a ≥ 4
You can use the number axis to help solve. Draw the range of two sets on the number axis

Given the set a {Y / y square - (a * a + A + 1) y + a (a * a + 1) > 0} B {Y / y = 1 / 2x square - X-5 / 2,0 ≤ x ≤ 3} if a intersects B = empty set, find the value range of a
Come on, it's urgent
thank you

First, find the formula y = 1 / 2 (x ^ 2-2x + 1) - 3 = 1 / 2 (x-1) ^ 2-3 of set B, because if 0 ≤ x ≤ 3, then x = 1, y takes the minimum value of - 3, x = 3, y takes the maximum value of - 1 - 3 ≤ y ≤ - 1, and then find the factorization (Y-A) (Y - (a * a + 1)) > 0 of set A. discuss the size difference formula a * a + 1-A = (a * A-A + 1

Given a = {- 1,1,2}, B = {x | x square - 2x = 0}, then a intersects B=

It is equal to {2}

How to express the set of solutions of equation x's Square - 2x + 3 = 0 by descriptive method?

{x | x ^ 2-2x + 3 = 0, X belongs to R}

Solve the equation about X: the square of x-2x + 1-k (the square of x-1) = O

（x-1）²-k(x-1)(x+1)=0
(x-1)[x-1-k(x+1)]=0
X = 1 or (1-k) x = 1 + k
Understand? Change your mind and try what you know

We know the square of the equation 2x about X - (4K + 1) x + 2K Square-1 = 0
When k is what value
(1) The equation has two unequal real roots
(2) The equation has two equal real roots
(3) The equation has no real roots

The solution is Δ = (4K + 1) &# 178; - 4 × 2 × (2k & # 178; - 1)
=16k²+8k+1-16k²+8
=8k+9
That is, (1) when k ＞ - 9 / 8, Δ ＞ 0, that is, the equation has two unequal real roots
(2) When k = - 9 / 8, Δ = 0, that is, the equation has two equal real roots
(3) When k is less than - 9 / 8, Δ is less than 0

The solution of the equation x squared + X squared equals 2 is a process!

x^2+1/x^2=2
x^2-2+1/x^2=0
(x-1/x)^2=0
x-1/x=0
x=1/x
x^2=1
X = plus or minus 1

Equation 2x-y = 0, xsquare-ysquare + 3 = 0

From 2x - y = 0, we can get y = 2x, bring it into the second equation, X * x-4x * x + 3 = 0, and get x = - 1 or 1, corresponding y = - 2 or 2

y -0.4y=28.8
3.5m + m =7.65
9 * 17 + 9a=36.9
(x -5.5) / 3 =21.5

1. y-0.4y=28.8 2. 3.5m+m=7.65 3. 9×17+9a=369
Solution: 1y-0.4y = 28.8 solution: 3.5m + 1m = 7.65 solution: 153 + 9A = 369
(1-0.4)y=28.8 (3.5+1)m=7.65 153+9a-153=369-153
0.6y=28.8 4.5m=7.65 9a=216
0.6y÷0.6=28.8÷0.6 4.5m÷4.5=7.65÷4.5 9a÷9=216÷9
y=48 m=1.7 a=24
4. (x-5.5) △ 3 = 21.5 in order to see more clearly, so it is written in such detail,
Solution: (x-5.5) △ 3 × 3 = 21.5 × 3 hehe, don't think
x-5.5=64.5
x-5.5+5.5=64.5+5.5
x=70

Random points, such as 2% x + 4% x = 9
4%x =9
X = 9 divided by 0.04
x=225

2% x + 4% x = 6% x, then 9 / 6% = 9 / 0.06 = 100, so x = 150