The second power of x plus 10x plus 21 is equal to zero, so we can solve the equation Such as the title, urgent

The second power of x plus 10x plus 21 is equal to zero, so we can solve the equation Such as the title, urgent

x^2+10x+21=0
(x+3)(x+7)=0
x+3=0
x+7=0
The solution is X1 = - 3, X2 = - 7

To solve the equation with the method of collocation, the square of 3 / 4 x plus 3 x is the same as the problem

3/4x^2+3x=1,x^2+4x=4/3,(x+2)^2=4+4/3,(x+2)^2=16/3.x+2=+-4√3/3,x= +-4√3/3-2

The square of 10x-x is 21, so we can solve the equation,

The square of 10x-x is 21
x^2-10x+21=0
(x-3)(x-7)=0
X = 3 or 7

A factory originally planned to produce a batch of parts in 26 days. After working for 2 days, due to the change of operation method, it produced 5 parts per day, which was 4 days ahead of the original time
Task, how many parts are planned to be produced tomorrow?

If x parts were produced every day, now x + 5 parts are produced every day
26x=2x+(x+5)*(26-2-4)
The solution is x = 25

Someone originally planned to produce a batch of parts in 26 days. After working for 2 days, due to the change of operation method, he produced 5 more parts per day than before, and the result was completed 4 days ahead of schedule
How many parts are produced every day? How many parts are there in this batch?

Set the original production x per day
26 x = 2x +20(x+5)
x = 25
26x = 650
The original daily production of 25, this batch of parts a total of 650
If you don't understand, you can ask

A worker originally planned to produce a batch of parts in 26 days. After working for 2 days, due to the change of operation method, he produced 5 more parts every day and finished the task 4 days ahead of schedule. How many parts were produced every day? How many parts are there in this batch? (answer the equation)

Set the original production x per day
26 x = 2x +20(x+5)
x = 25
26x = 650
The original production of 25 per day, a total of 650 parts

A factory originally planned to produce a batch of parts in 26 days. After 2 days of work, due to the change of operation method, it produced 5 more parts per day than before, and finished the task 4 days ahead of time
How many parts are produced per day? How many parts are there in this batch

Set the original production of X parts per day
26x=2x+(26-2-4)(x+5)
26x=2x+20(x+5)
26x=2x+20x+100
4x=100
x=25
25×26=650
The original production of 25 parts per day, this batch of parts 650

Two people planned to produce a batch of parts in 26 days. After working for 2 days, because of the change of working method, they produced 5 more parts every day than before. As a result, they finished the task 4 days ahead of schedule. How many parts were originally planned to produce every day? How many parts are there in this batch?

Set the original production x per day
26x=2x +20(x+5)
x=25
26x = 650
It turned out that 25 pieces were produced every day, and there were 650 pieces in total

For a batch of parts, it is planned to produce 60 parts per day and complete them in 30 days. In fact, 15 more parts per day are produced and how many days are actually used? (solved by equation)

It took X days
60×30=（60+15）x
1800=75x
x=24
That is: the actual use of 24 days

Master Wang plans to produce a batch of parts in 30 days. In fact, he produces 60 more parts per day than planned. In this way, he completes the task five days ahead of schedule. How many parts are there?

60 × (30-5), = 60 × 25, = 1500 (pieces), 1500 ／ 5 × 30, = 300 × 30, = 9000 (pieces); a: there are 9000 parts in this batch