24 minutes =0.4 hours
Armored vehicles travel x kilometers per hour.
72/(x- 15)-72/x=0.4
180/(x- 15)- 180/x = 1
180 x- 180(x- 15)= x(x- 15)
x^2- 15x-2700=0
(x-60)(x+45)=0
X=60 x=-45 (irrelevant)
x- 15=45
A speed is 60 km/h and B speed is 45 km/h.
A factory produced 500,000 finished products in the first month of the fourth quarter. In order to increase the number of products, it produced 6.5438+0.75 million finished products in the fourth quarter. What is the average growth rate in the fourth quarter 1 1 and 65438+February?
Let 1 1 and 65438+the average growth in the fourth quarter of February be x.
50+50( 1+x)+50( 1+x)^2= 175
50+50+50x+50+ 100x+50x^2= 175
50x^2+ 150x-25=0
x^2+3x-0.5=0
x=(-3 √ 1 1)/2
X=(-3-√ 1 1)/2 (negative values are rounded off)
x =(-3+√ 1 1)/2 =(-3+3.3 166)/2 = 0. 1582 = 15.82%
The average growth rate in the fourth quarter 1 1 and 65438+February was 15.82%.
3. It is known that a= radical number 5+ 1,
Calculate (a square -2a-3) points (a square -2a+ 1).
= the square of (a-3) (a+1) (a- 1)
= (√ 5+1-3) (√ 5+1+1) percent squared.
=(√5-2)(√5+2) √5 square percentage.
=5
4. It is known that A and b(a is not equal to B) meet the conditions.
A square -7a+2=0,
Square of b -7b+2=0
The square of a-7a = the square of b -7b.
(a+b)(a-b)-7(a-b)=0
(a-b)(a+b-7)=0
a=b a+b=7
When a=b
b/a+a/b= 1+ 1=2
When a+b=7, Ab=2.
b/a+a/b
= (Party A+Party B) /ab
=[(a+b)-2ab]/ab
=[7-2*2]/2
= 1.5