Given the function f (x) = ax ^ 2 + X + blnx, take the extremum at x = 1 and x = 2 and find a and B

Given the function f (x) = ax ^ 2 + X + blnx, take the extremum at x = 1 and x = 2 and find a and B

f'(x)=2ax+1+b/x
f'(1)=0
2a+1+b=0
b=-2a-1.(1)
f'(2)=0
4a+1+b/2=0
8a+2+b=0.(2)
(1) Substituting (2): 8A + 2-2a-1 = 0
6a=-1
a=-1/6
Substituting (1)
b=-2(-1/6)-1
=-2/3

There is also a formula, what is the maximum minus the minimum, but also in addition to: do not remember, do not understand the grouping
What else is there in the group,

Frequency: the number of times a data appears in a sample
The maximum minus the minimum is also divided by group distance = number of groups

How much is ninety-nine and eighteen seventeen times minus eighteen,

Pro, I'll answer for you. Ninety nine and seventeen out of eighteen are Mongolian. It's true to write 100-1 / 18, and then it's resolved into (100-1 / 18) * - 18 = - 1799

Linear equation of one variable
A machine originally planned to process a batch of parts in 13 hours. Because of the urgent task, it decided to process 6 more parts per hour. In this way, it completed the task in 12 hours, and produced 48 more parts than the original plan. How many parts did it plan to process?

The original plan is to process x parts per hour, and the total number of parts processed is 13X
12(x+6)=13x+48 x=24
13x=312
A: it was originally planned to process 312

2.07 divided by 0.023 and 111 divided by 0.3,

The problem of mathematical contagion in grade three of junior high school

Let the number of infected persons be (1 + x) ＾ n

153 ° 19 ′ 41 ″ + 20 ° 43 ′ 48 ″ (to be calculated)

153°19′41〃
+ 20°43′48〃
______________
174° 3′ 39〃

If the solution AX = 3 of the equation of X is a natural number, then the value of integer a is___

A = 1, where x = 3
Or a = 3, where x = 1

Simple calculation: 0.36 * 8.1 + 3.6 * 0.81
0.36*8.1+3.6*0.81

0.36*8.1+3.6*0.81
=0.36*8.1+0.36*8.1
=2*0.36*8.1=5.832

5x-9y=2 x-2y=5

From 5x-9y = 5
x=1+9y/5
Substitute 2x-2y = 5 to get
2 + 18y / 5-2y = 5
y=15/8
Substitute x = 1 + 9y / 5 to get
x=35/8