The square of the difference between 2 times of a number and 3 is equal to the sum of the square of the number and 9. What is the number?

The square of the difference between 2 times of a number and 3 is equal to the sum of the square of the number and 9. What is the number?

This number is set to X
There are: (2x-3) ^ 2 = x ^ 2 + 9
We get X1 = 0, X2 = 4
This number is 0,4

The square of a number is equal to the number multiplied by 6

Let X be the number
x²=6x
x²-6x=0
x(x-6)=0
The solution is: x = 0 or x = 6
A: this number is 0 or 6

1 times 2 times 3 times. Multiply n + 3 is a complete square number. What is the minimum of N?
1 * 2 * 3 *... * n is a complete square number, then what is n equal to?

I haven't found that n satisfies 1 * 2 * 3 *... * n = n! Is a complete square
We know that 3 is a prime number, so the satisfaction is at least > 2 * 3 = 6. As long as we pass through a prime number x, then n must not be less than 2x, and 3

How to use triangle method in force analysis?
I don't use it very much,
How to use triangle knowledge to solve problems? If you know the magnitude of the two forces, but you don't know the magnitude of the third force, and there is no right angle side, how can you find the third force?

Triangle rule is the use of vector translation, learning vector is easy to understand, if not, is to let the direction of the force unchanged, and translation makes three forces into a triangle, using triangle knowledge to solve problems

There are 152 students in the sixth grade of the experimental primary school. Now we have to select 111 boys and 5 girls to meet with experts at the International Congress of mathematicians. After the school has selected several representatives according to the above requirements, the number of the remaining boys and girls is equal. Q: how many boys are there in the sixth grade of the experimental primary school?

A super simple math problem for senior one
In triangle ABC, if B ^ 2 > A ^ 2 + C ^ 2, what triangle is triangle ABC?

Using cosine theorem
cosB=(a^2+c^2-b^2)/(2ac)
Know from the topic
a^2+c^2-b^2

Given that the image of the function f (x) = x ^ 3 + BX ^ 2 + CX is tangent to the X axis at a point other than the origin, and the minimum point of the function f (x) is - 1, find the value of B and C

When do you use subtraction!
I will add and subtract elimination method ~ just self-taught ~ when to use them to subtract, when to use them to add ~ make it clear ~ give an example~

1, for example
3x+4y=7;
3x+2y=5.
Just use subtraction (subtracting from 2) to get rid of X
2. For example
3x+4y=7;
x-4y=-3.
Just add (2-way addition), you can eliminate y
[the criterion to judge whether to add or subtract is to eliminate the unknowns]

The range of y = x ^ 3-6x + 9 on [- 1,4] is solved by derivative method

Y '= 3x & sup2; - 6 let y' = 0, that is, 3x & sup2; - 6 = 0 solution, x = ± radical 2 in [- 1,4], only x = radical 2 is the extreme point, when x = radical 2, y = 2 (radical 2) - 6 (radical 2) + 9 = 9-4 (radical 2), when x = - 1, y = - 1 + 6 + 9 = 14, when x = 4, y = 64-24 + 9 = 49, so in the interval [- 1,4], the maximum value is 49, and the minimum value is (9

150 mental arithmetic questions, no software

360 ÷3 ＝
42× 20＝
12 × 50＝
1500－700＝
5900－4000＝
76 ＋ 27＝
840 ÷ 2＝
770 ÷ 7＝
30× 20＝
40× 50＝
9900+100＝
700 ÷ 7＝
240× 10＝
390 ÷ 3＝
60× 50＝
71 - 22＝
50 × 90＝
14 × 20＝
600＋1200＝
840 ÷ 4＝
36 ＋ 49＝
10 × 60＝
800 × 50＝
180 ÷ 3＝
120 ÷ 6 ＝
7500+500＝
460＋140＝
33 × 20 ＝
990 ÷ 3 ＝
440 ÷ 4 ＝
83-57 ＝
860 ÷ 2＝
1100－600＝
6900－1900＝
720 ÷ 8＝
0÷999＝
7 × 800＝
23 × 30＝
290 －190＝
690 ÷ 3＝
690÷3×6＝
17×40＝
100－63＝
3.2＋1.68＝
2.8×0.4＝
14－7.4＝
1.92÷0.04＝
0.32×500＝
0.65＋4.35＝
10－5.4＝
4÷20＝
3.5×200＝
1.5－0.06＝
0.75÷15＝
0.4×0.8＝
4×0.25＝
0.36＋1.54＝
1.01×99＝
420÷35＝
25×12＝
135÷0.5＝
3/4 + 1/4 =
2 + 4/9 =
3 - 2/3 =
3/4 - 1/2=
1/6 + 1/2 -1/6 =
7.5-(2.5+3.8)=
7/8 + 3/8 =
3/10 +1/5 =
4/5 - 7/10 =
2 - 1/6 -1/3 =
0.51÷17＝
32.8＋19＝
5.2÷1.3＝
1.6×0.4＝
4.9×0.7＝
1÷5＝
6÷12＝
0.87－0.49＝
24/3*9=
15*3-20=
12*11+13=
25*4+36=
36+25-14=
2*36+4=
12/4*35=
(23-8)*3=
14/2+21/3=
42/14+54/9=
55/11*20=
36/9*12=
16/4*19=
16-45/15+6=
70÷7=
20×10=
320÷5≈
54×70≈
251÷4≈
6300÷7=
131÷4≈
50×8=
85-45=
0÷5=
280÷4=
60×40=
840-30=
2700÷9=
99×31≈
3.1＋2.7=
131÷4≈
50×8=
7.8-1.8=
350÷5=
630÷9=
131÷6≈
10×80=
65-56=
431÷6≈
15×6=
4.8-0.4=
6.1＋0.7=
91×18≈
257÷4≈
44÷4=
20×40=
210-30=
34+28 =
63- 63÷9=
120÷3×2=
800÷8=
40×70=
300÷4≈
59×72≈
251÷5≈
630÷7=
131÷6≈
0×108=
45-18=
0÷15=
120÷4=
30×40=
640-70=
1800÷9=
99×39≈
5.1＋2.6=
411÷4≈
15×20=
7.3-1.8=
250÷5=
6300÷9=
431÷6≈
20×80=
78-56=
491÷8≈
14×6=
4.8-4.4=
6.1＋4.7=
91×19≈
367÷4≈
55÷5=
10×40=
211-30=
134+28 =
50×40-100=
12×20÷30=