4.8 * 15.4/1.6/0.77 how to calculate easily?

4.8 * 15.4/1.6/0.77 how to calculate easily?

Take it as (4.8 / 1.6) * (15.4 / 0.77) = 3 * 20 = 60

How to calculate 75 * 37 + 77 * 33

75*37+77*33
=75*37+75*33+2*33
=75*70+66
=5250+66
=5316

Simple operation: 33 × 37

33×37
＝﹙35－2﹚﹙35＋2﹚
＝35²－4
＝﹙30＋5﹚²－4
＝30²＋2×30×5＋5²－4
＝900＋300＋25－4
＝1221

Practical problems of quadratic function in Junior Three
The distance between the image of quadratic function and the two intersections of X axis is 2, and it passes through (2,1), (- 1, - 8) two points, so the analytic expression of quadratic function can be obtained

y=ax²+bx+c(x1-x2)²=(x1+x2)²-4x1x2=(b/a)²-4c/a=2².① 4a+2a+c=1.②a-b+c=-8.③a=-9,b=12,c=13.y=-9x²+12x+13a=-1/5,b=16/5,c=-23/5.y=-x²/5+16/5x-23/5

If I give you a table, how can I tell whether the function is a quadratic function or a linear function or an inverse proportion function?

1. First try the function with two sets of corresponding values, and then see if other points are on the line, if it is a function
Otherwise:
2. Try the inverse proportional function again to see if the products of the corresponding values of each group are equal
Otherwise:
3. Take three groups of corresponding values and use the undetermined coefficient method to find the analytic formula of quadratic function

Second grade mathematics application problem is urgent! Please answer in detail, thank you! (14 16:46:46)
Xiao Wang bought several boxes of milk of a certain brand with 24 yuan in the supermarket. After a while, he went to the supermarket and found that the milk was sold at a profit of 0.4 yuan per box. He also bought two more boxes with 24 yuan than last time. If he bought x boxes for the first time, the equation can be set up as follows: 160; 160; 160; 160; 160; 160; 160; 160

If he bought X-box for the first time, then the equation can be listed
24/x-0.4=24/(x+2)
X = - 12 (rounding off)
x=10
He bought 10 boxes for the first time