The straight line y = X-2 and the parabola y2 = 2x intersect at two points a and B, and prove that OA ⊥ ob (o is the coordinate origin)

The straight line y = X-2 and the parabola y2 = 2x intersect at two points a and B, and prove that OA ⊥ ob (o is the coordinate origin)

It is proved that y2-2y-4 = 0 ∧ Y1 + y2 = 2, y1y2 = - 4 ∧ x1x2 = (Y1 + 2) (Y2 + 2) = y1y2 + 2 (Y1 + Y2) + 4 = 4 ∧ y1y2x1x2 = - 1, that is, (Y1 / x1) (Y2 / x2) = - 1koa = y1x1, kob = y2x2 ∧ KOA · kob = y1y2x1x2 = - 1 ∧ OA ⊥ ob

The formula of encounter problem
It's better to write in full

The common formula in primary school is sum difference problem (sum + difference) / 2 = large number (sum difference) / 2 = decimal sum multiple problem and (multiple-1) = decimal × multiple = large number (or sum decimal = large number) difference multiple problem difference (multiple-1) = decimal × multiple = large number (or decimal + difference = large number) tree planting problem 1

The trajectory equation of a point in the plane whose distance from point a (1, - 1) is equal to root 5 is

It is a circle with a as the center and R = √ 5
So it's (x-1) &# 178; + (y + 1) &# 178; = 5

(the third power of 1-Q)

1-q^3=(1-q)(1+q+q^2)

Suppose August 23, 2011 is Monday and October 3, 2012 is Sunday ()
Don't look at the calendar

From August 23, 2011 to August 23, 2012, it's 366 days
From August 23 to October 3, 2012 is 41 days
The total interval is 407 days
407 is 58 weeks and one day
If August 23, 2011 is Monday
So October 3, 2012 is Tuesday

Physics problems, detailed solution process, and the formula used
1: A certain bulb is marked with pz220 40W. PZ is the abbreviation of ordinary lamp. Its rated power is? W. when it normally emits light, its working current is? A filament resistance? Ohm. Detailed answers and formulas are required
2: The resistance of a resistance wire is 12 ohm. When the voltage applied at both ends of the resistance wire is 36V, the electric power is? Working for 5min, and the electric energy consumption is?

(1) The amount of P is 40W written on "pz220 40W"
I actual = P actual / u actual = 40W / 220V = 0.18a (about)
R = u / I = 220V / 0.18a = 275 ohm
(2) I = u / r = 36V / 12 ohm = 3A
P=UI=36V*3A=108W
Unit: 5min = 300s
W=P*T=108W*300S=32400J

There are four Wednesdays and five Tuesdays in June of a certain year. What day is June 1 of this year?

There are five Tuesdays, so there are 29 days from the first week to the Fifth Tuesday. There are 30 days in June, and the remaining day can only be before the first Tuesday, but not after the Fifth Tuesday, that is, at the point of the figure, which happens to be June 1. So June 1 of this year is Monday

A chemical literal expression of grade three in junior high school
Copper sulfate solution was dropped into hydrogen peroxide solution as catalyst
It's a literal expression
And it should not be as complicated as 1L
We haven't learned chemical equations yet

Hydrogen peroxide = = copper sulfate = = water + oxygen
The customer is God. Is that ok?

How many numbers are there within 1000, divided by three to two, divided by five to three, divided by seven to four?

Answer separately

Mathematical formulas and concepts in the first semester of grade seven
I can't find my math book in the first semester of seventh grade
It's best to copy it from the first term math book of grade seven
(a bit of trouble)

Rational numbers can be divided into integers and fractions. Integers can be divided into positive integers, zeros and negative integers. Fractions can be divided into positive and negative fractions. 3