English translation A very popular breakfast food in America is the pancake---a thin,flat cake made out of flour and often served with maple syrup.The idea of the pancake is very old.In Fact, pancakes were made long ago in ancient China!

English translation A very popular breakfast food in America is the pancake---a thin,flat cake made out of flour and often served with maple syrup.The idea of the pancake is very old.In Fact, pancakes were made long ago in ancient China!

Pancakes are very common breakfast food in the United States. They are made of thin flour. People often eat them with maple syrup. The habit of eating pancakes has a long history. In fact, pancakes were made in ancient China a long time ago

It is known that f (x) = x ^ 2-3ax ^ 2-3x + 1
1) Let a = 2, find the monotone interval of F (x)
2) Let f (x) have at least one extreme point in the interval (2.3), and find the value range of A
The first question is better to use derivative

1) F (x) = x ^ 2-3ax ^ 2-3x + 1 = x ^ 2-6x ^ 2-3x + 1 = - 5x ^ 2-3x + 1 = - 5 (x-3 / 10) ^ 2 + 1 + 9 / 20 = - 5 (x-3 / 10) ^ 2 + 29 / 20f (x) = - 5 (x-3 / 10) ^ 2 + 29 / 9 monotone interval (- ∞, 3 / 10), [3 / 10, + ∞) f (x) = 5x ^ 2-3x + 1F '(x) = 10x-3 = 0x = 3 / 10 monotone interval (- ∞, 3 / 10), [3

First read the following knowledge, and then answer the question: the equation with an unknown number and the highest degree of the unknown number is 2 is called the univariate quadratic equation, such as: x2-2x + 1 = 0. The known root of the univariate quadratic equation AX2 + BX + C = 0 (a, B, C represent constants, a ≠ 0) about X is: ① when b2-4ac > 0, the equation has two unequal real roots; ② when b2-4ac = 0, the equation has two unequal real roots There are two equal real roots (i.e. one root); ③ when b2-4ac ＜ 0, the equation has no real roots; solutions: (1) judge the case of 2x2 + 4x + 5 = 0 real roots. (2) when k takes what value, the equation x2-2x + (K-4) = 0 has two unequal real roots

(1) ∵ (?) = 42-4 × 2 × 5 = - 24 ＜ 0, the univariate quadratic equation 2x2 + 4x + 5 = 0 has no real roots; (2) ∵ the univariate quadratic equation x2-2x + (K-4) = 0 about X has two unequal real roots, ∵ = (- 2) 2-4 (K-4) ＞ 0, and the solution is k ＜ 5. That is, when k ＜ 5, the univariate quadratic equation x2-2x + (K-4) = 0 about X has two unequal real roots

Galaxy solar system earth universe moon____________________________________ From big to small

Universe Galaxy Solar System Earth Moon

2.25x minus 3.6 equals 6.4

2.25%X=6.4+3.6
2.25%X=10
X=10÷0.0225
X = 10000 out of 0.0225

The direction of friction and the two conditions for friction

There are four conditions for friction
First of all, contact. Second, the contact surface must be rough (and both surfaces must be rough, not smooth on one side). Then, there must be pressure. Finally, there must be relative motion or relative motion trend, which is indispensable
The direction of friction is always opposite to the direction of relative motion (or its trend)

How to calculate that 0.3 of 0.5 is equal to x + 1 of 2x-1?

0.3(2x-1)=0.5(x+1)
0.6x-0.3=0.5x+0.5
0.1x=0.8
x=8
That's how it works

Two trains a and B leave 1000 kilometers apart at the same time and travel in opposite directions. Six hours later, the two trains are 130 kilometers apart, with 85 kilometers per hour for train a and how many kilometers per hour for train B?

(1) (1000-130) △ 6-85, = 870 △ 6-85, = 145-85, = 60 (km); answer: car B travels 60 km per hour. (2) (1000 + 130) △ 6-85, = 1130 △ 6-85, = 18813-85, = 10313 (km); answer: car B travels 10313 km per hour

AB is two natural numbers, which satisfy the following conditions at the same time: 11 / 7 < A / b < 1 / 62 A + B = 22
What's more, a number minus 2 / 15, plus 1 / 3, and the sum is 4 / 5, what's the number? It's calculated by the formula

57 0.6

Factorization 999 & sup2; + 999 × 2 + 1 (A-2) (A-3) + 5a-42

(1)=(999+1)^2=1000^2=10^6
(2)=a^2-5a+6+5a-42=a^2-36=(a-6)(a+6)