Three times the sum of a number and six equals 21 to find a number

Three times the sum of a number and six equals 21 to find a number

Some number = 21 △ 3-6 = 1

Given 1 + 2x Λ 3-3x Λ 2 = 3Y, find x = f (y)

In this paper, we are going to find the following stationary point coordinates: F 39; X = 6xy-6x-6x = 6xy-6x = 6xy-6x = 0g (1) f; X; X = 6xy-6x = 0g (1) f; y = 3x ＾ 2x ＾ 2Y ＾ 2Y ＾ 2x ＾ 3-3x x ＾ 2 ＾ 2 ＾ 2 ＾ 2x ＾＾＾＾＾＾＾＾＾ 2 ＾＾ 2 ＾＾ 2 ＾ 2 - 6, f ＆ 39; xy = 6x, F ＆ 39; YY = 6y-6. (1) x = y = 0A = f ＆ 39; & 39; XX (0,0) = - 6 ＆ lt; 0, B = f ＆ 39; & 39; XY (0,0) = 0, C = f ＆ 39; & 39; YY (0,0) = - 6, AC-B ＾ 36 ＆ gt; 0, f (x, y) takes the maximum value 2 at (0,0); the rest is for your practice

How to calculate 2.4:1.6 = 12: X ratio

2.4:1.6=12:x
2.4X=1.6×12
2.4X=19.2
X=19.2÷2.4
X=8

29 of 36-24 of 13, 8 of 15-4 of 1, 5 of 14 + 3 of 16

7-2 / 20 = 21 / 60-8 / 60 = 13 / 60;
29-24 out of 36 = 58 / 72-39 / 72 = 19 / 72;
8 / 15-1 / 4 = 32 / 60-15 / 60 = 17 / 60;
5 out of 14 + 3 out of 16 = 40 / 112 + 21 / 112 = 61 / 112
If you don't understand this question, you can ask,

Find the left and right limits of F (x) = x / X.G (x) = | x | / X. when x tends to 0, and explain whether their limits exist when x tends to 0

The left and right limits of F are equal to 1, so the existence of limit is equal to 1
But the left limit of G is - 1 and the right limit is 1, so the limit does not exist

X-15% x = 1.7 (solving equation)

(1-15%)X=1.7
X=1.7x100/85
X=2
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Find the law 1 / 2,1,1 / 3,4 / 3,4 / 15, (), (),

1/2,1,1/3,4/3,4/15,(8/5),(8/35),...
Solution: from the previous number to * 2, / 3, * 4, / 5, * 6, / 7..., namely:
(1/2)*2=1
1/3=1/3
(1/3)*4=4/3
(4/3)/5=4/15
(4/15)*6=8/5
(8/5)/7=8/35...

Given the function f (x) = (x-1) ^ 2, the sequence an is the arithmetic sequence with tolerance D, and BN is the arithmetic sequence with common ratio Q. if A1 = f (D-value)
1) , A3 = f (D + 1), B1 = f (Q-1), B3 = f (Q + 1) (I) find the general formula of sequence an and BN; (II) let CN have C1 / B1 + C2 / 2B2 + for any natural number n +Cn / NbN = an + 1, find C1 + C3 + +Sum TN of C (2n-1)

a3-a1=2d=f(d+1)-f(d-1)
=d^2-(d-2)^2
=4d-4
So 2D = 4 --- > d = 2
a1=f(2-1)=f(1)=(1-1)^2=0
So an = 2 * (n-1)
b3/b1=q^2=q^2/(q-2)^2
Q-2 = 1 or Q-2 = - 1
We get Q1 = 3 or Q2 = 1
When Q1 = 3, B1 = 4 --- > BN = 4 * 3 ^ (n-1)
When Q2 = 1, B1 = 1 --- > BN = 1 is a constant sequence

Calculate definite integral ∫ upper limit 2 lower limit - 2 integrand function max {1, x ^ 2} thank you!

The original formula = ∫ - 2,1) x ^ 2DX + ∫ - 1,1) DX + ∫ (1,2) x ^ 2DX
=2∫(1,2)x^2dx+∫(-1,1)dx
=(1,2)|2x^3/3+(-1,1)|x
=2/3*(8-1)+(1+1)
=14/3+2
=20/3

What number should be filled in the blank? The first line is 9 3 18, the second line is 7 5 6, and the third line is 10 6
It's better to give a reason,

9 3 18
7 5 6
10 6 9