(x²-4)²-10(x²-4)+25

(x²-4)²-10(x²-4)+25

The original formula = [(X & # 178; - 4) - 5] &# 178;
=(x²-9)²
=[(x+3)(x-3)]²
=(x+3)²(x-3)²

Find the value of √ 25 + X & # 178; - √ 15 + X & # 178; = 4

Let a = √ 25 + X & # 178;
b=√15+x²
Then A-B = 4
And a & # 178; - B & # 178;
=25+x²-15-x²
=10
So (a + b) (a-b) = 10
So the original formula = a + B = 5 / 2

A and B start from two places 90 kilometers apart at the same time. After 3 / 2 hours, the two vehicles meet on the way. Car a travels 60 kilometers per hour and car B travels 60 kilometers per hour

It should be 2 / 3 hours, right?
90/（2/3）-60=75
Car B 75 km / h

Square root Pythagorean theorem formula?

a. B is the right angle side, C is the hypotenuse, a ^ 2 + B ^ 2 = C ^ 2

The two trains, a and B, set out at the same time from a and B, which are 360 kilometers apart. After meeting each other, a passed by 4
The two trains, a and B, set out at the same time from a and B, which are 360 kilometers apart. After meeting, a arrives at B in four hours, and B arrives at B in nine hours. What's the speed of a and B?

Let t be the time from starting to meeting
[360/(t+4)]t+[360/(t+9)]t=360
t^2=36
So t = 6
So the speed of a is 360 / (6 + 4) = 36km / h
The speed of B is 360 / (6 + 9) = 24km / h
Or let the velocity of a be x and the velocity of B be y
360/x-4=360/y-9；（360/x-4）*（x+y）=360
Simultaneous equations
x=36,y=24

If the average of data a + 1, B + 2, C + 3 is 6, then the average of data a, B, C is ()

The average of a + 1, B + 2 and C + 3 is 6, then a + B + C + 1 + 2 + 3 = 6 * 3
So a + B + C = 6 * 3-1-2-3 = 12
a. The average of B and C is 12 / 3 = 4

The positive and even numbers are arranged in 5 columns according to the following table?
2 4 6 8
16 14 12 10
18 20 22 24
32 30 28 26
A. Line 125 column 1 B line 125 column 5
C. Line 250 column 4 C line 250 column 2

c

There are two three digit numbers, each of which is a different prime number, and this number can be divided by 2 and 3. What are the two three digit numbers?

732.372

The two cars started from the two places at the same time and ran in opposite directions. Three hours later, they met at a distance of 15 kilometers from the midpoint of the two places. It is known that the express train runs 88 kilometers per hour,
equation

When they met, the express train traveled 15 × 2 = 30 kilometers more than the local train
Every hour, express trains travel 30 △ 3 = 10 km more than local trains
Slow speed: 88-10 = 78 km / h
Set the idle speed to x km / h
3(88-x)=15×2
3(88-x)=30
88-x=10
x=88-10
x=78
A: the local speed is 78 km / h

As shown in the figure, in the quadrilateral ABCD, ad ∥ BC, ab ∥ DC, what is the size relationship between ∥ a, ∥ B, ∥ C and ∥ D?
There has to be a process,

Because AB / / DC
Therefore, a + D = 180 degree
And because of AD / / BC, AB / / DC
So the quadrilateral ABCD is a parallelogram
Therefore, B = D
And because of AD / / BC
Therefore, C + D = 180 degree