3x / 0.5 - 2-x/0.4 = 1

3x / 0.5 - 2-x/0.4 = 1

3x / 0.5 - 2-x/0.4 = 1
6x - 2 - 2.5x = 1
3.5x = 3
x = 6/7

3x-7（x-1）=3-2（x+3）．

Remove the brackets to get: 3x-7x + 7 = 3-2x-6 move item: get 3x-7x + 2x = 3-6-7 merge similar items: - 2x = - 10 coefficient into 1 get: x = 5

If X & # 178; + mx-14 can be divided by X + 2, find the value of M. if X & # 178; - 3x + 1 = 0, find the value of X & # 178; + x ^ - 2

x²+mx-14=(x+2)(x+n)=x²+(2+n)x+2n;
2+n=m;
2n=-14;
n=-7;
m=2-7=-5;
x²-3x+1=0;
x-3+1/x=0;
x+1/x=3;
x²+x^-2=(x+1/x)²-2=9-2=7;

[x | X & # 178; + MX + 1 ≤ 0} is contained in {x | X & # 178; - 3x + 2 ≤ 0}, and the range of M is obtained

Because {X / X & # 178; - 3x + 2 ≤ 0} = {X / 1 ≤ x ≤ 2} is set a; because set B = [x | X & # 178; + MX + 1 ≤ 0} is contained in set a; there are two cases: B is an empty set, B is not an empty set; (1) when B is an empty set, that is, X & # 178; + MX + 1 is always greater than 0; because the function y = x & # 178; + MX + 1 has an opening direction upward; to

Dongfeng construction company used two fifths of the original batch of cement on the first day, and transported another 48 tons. At this time, the cement is two-thirds of the original total. How many tons of this batch of cement?

48 △ 2 / 3 - (1-2 / 5)] = 48 △ 1 / 15 = 720 tons

In the triangular pyramid o-abc, the three edges OA, OB and OC are perpendicular to each other, and OA > ob > OC respectively pass through OA, OB and OC to make a section and divide the volume of the triangular pyramid equally. The section area is S1, S2 and S3 in turn, then the minimum value of S1, S2 and S3 is______ ．

Taking the midpoint D of BC, connecting od and ad, the planar oad bisects the volume of triangular pyramid, that is, the area of triangular oad is S1. In RT △ BOC, OD is the middle line on the hypotenuse BC, ∧ od = 12bc, ∧ OA ⊥ ob, OA ⊥ OC, ∧ OA ⊥ planar BOC, ∧ OA ⊥ OD, ∧ S1 = OA × 12od, that is, S12 = 14oa2od2 = 116oa2bc2 = 116oa2 (ob2 + oc2) = 116 (oa2ob2 + oa2oc2). Similarly, S22 = 116 (oa2 + oc2) can be obtained Ob2 + ob2oc2), S32 = 116 (oa2oc2 + ob2oc2), because OA > ob > OC, so S12 > S22 > S32, so the minimum value of S1, S2, S3 is S3

For the first time, 20% of the goods were transported. For the second time, 6 tons were transported. For the third time, 2 tons were less than the sum of the previous two times. This is one third of the remaining goods
How many tons of the goods are there?
Can you talk about it?

20% in the first time and 6 tons in the second time,
The third shipment is 2 tons less than the sum of the previous two, so
Three times
20%+6+（20%+6-2）
=40% + 10 tons
Because 1-1 / 3 = 2 / 3 of the goods have been shipped three times
The weight of the goods is:
10÷（2/3-40%)
=10÷（10/15-6/15)
=10÷4/15
=37.5 tons
A: there are 37.5 tons in total

If f (x) = 1 / radical (x ^ 2-ax + 3a) is a decreasing function in the interval [2, + infinity], what is the value range of a

Let g (x) = x ^ 2-ax + 3a
Let f (x) = 1 / radical (x ^ 2-ax + 3a) be a decreasing function in the interval [2, + infinity],
If G (x) = x ^ 2-ax + 3a is an increasing function in [2, + infinity] and greater than zero, then
G (x) axis of symmetry x = A / 20, the solution is a > - 4
So - 4

Female employees account for 35% of the total number of workers in a factory. There are 230 workers in the factory. How many male employees are there

230 × (1-35%) = 149.5 people, wrong data
Is the total number 320?
Male workers: 320 × (1-35%) = 208

Decomposition factor: 1.4x ^ 2-y ^ 2 + 4y-42. A-A ^ 3 + 4A ^ 2b-4ab ^ 2

1.4x^2-y^2+4y-4
=4x²-(y-2)²
=（2x+y-2)(2x-y+2)
2.a-a^3+4a^2b-4ab^2
=a[1-(a²-4ab+4b²)]
=a[1-(a-2b)²]
=a(1+a-2b)(1-a+2b)