Here is the question

Here is the question

（2）-5c-2a
5.C
(2) Original formula = 4x square - y square - 4 (x square - y Square)
=3Y square
(1) Original formula = (500-2) * (500 + 2)
=2500-4
=2496

1. If a > 0, then ()
A.a+2,a+5,2a+7
B.a+3,a+4,2a+5
C.a+1,a+6,2a+13
D.2a+9,a+4,a+2
2. In △ ABC, the minimum angle of the triangle is ()
A.30° B.36° C.40° D.44°

1. The requirement of triangle is that the sum of two sides is greater than the third side
A + 2 + A + 5 = 2A + 7
B yes
C is not a + 1 + A + 6A + 4 + A + 2
2. The sum of internal angles of triangle is 180 degrees, so ∠ B + ∠ C + ∠ a = 180
Because ∠ B = ∠ C = 2 ∠ a, 2 ∠ a + 2 ∠ a + a = 180, ∠ a = 36
The minimum angle is ∠ a = 36
Choose B

A highway is 365 kilometers long. A car travels 65 kilometers in the first hour, one fifth of the rest in the second hour, and how many kilometers in the second hour

(365-65) x 1 / 5 = 60 km

Given that the terminal edge of angle α passes through the point (3m-9, M + 2), and sin α > 0, cos α ≤ 0, the value range of M is obtained

The point is in the second quadrant or on the positive half axis of Y
3m-9≤0
m+2>0
-2

When a batch of cement is delivered to the construction site, 30% of it will be used on the first day
25% of the total number of cement transported in the second time, 400 tons more cement transported in the first time than in the second time. How many tons of this batch of cement?

No problem, can't solve, please show me the problem

It is known that the side length of a triangle is three continuous natural numbers. Find the side length of the triangle

Let the three sides of the obtuse triangle be n, N + 1, N + 2; the obtuse angle be a; from the cosine theorem, we know that (n + 2) & sup2; + (n + 1) & sup2; - 2n (n + 1) cosa, and get cosa = (n - 3) / 2n. Since angle a is an obtuse angle, so cosa < 0, then n-3 < 0; and N ∈ n, then n = 1 or n = 2

The ratio of cement, sand and stone is 2:3:5. If 34 tons of cement is used to mix concrete, how many tons of sand and stone are needed

2 + 3 + 5 = 10, 34 △ 210 = 3.75 (tons); yellow sand: 3.75 × 310 = 1.125 (tons); stone: 3.75 × 510 = 1.875 (tons); answer: it needs 1.125 tons of yellow sand and 1.875 tons of stone

If the function f (x) = (x + a) (x-4) is even, then the real number a=______ ．

Because the function f (x) = (x + a) · (x-4) is even, so ∀ x ∈ r has f (- x) = f (x). So ∀ x ∈ r has (- x + a) · (- x-4) = (x + a) · (x-4), that is, X2 + (4-A) x-4a = x2 + (A-4) x-4a, so a = 4

There are 56 people in class 61 and 30 people in class 62. How many people can be transferred from class 61 to class 62 to make the number of class 62 less than twice that of class 61 by 10!

If x people are transferred from class 61 to class 62, the number of class 62 will be 10 less than twice that of class 61
30+X=2(56-X)-10
30+X=112-2X-10
X+2X=112-10-30
3X=72
X=24
Only when 24 people are transferred from class 61 to class 62 can the number of class 62 be 10 less than twice that of class 61

If x, y ∈ R and X / 3 + Y / 4 = 1, then XY is the maximum

x/3+y/4>=2√xy/12 √xy