Answers to page 30 of the mathematics exercise book of the people's Education Press

Answers to page 30 of the mathematics exercise book of the people's Education Press

1.d2.b3.c 4.-12,-10,0 5.-0.25 6.0 7.35,-360,-4.32,21.6

Answer to question 13 of exercise book 9.10 of the first semester of junior high school mathematics
(x-3) (X-5) - 3 (x-1) (x + 3) (a + 2b-3) (a-2b + 3) (2x-y) (3x-2y) + (Y-X) (2x-5y) (2x-1) (2x + 1) (the second power of X + X + 1)

1, (x-3) (X-5) - 3 (x-1) (x + 3) = the square of X - 8x + 15-3 (the square of X + 6x-9) = the square of X - 8x + 15-3x - 6x + 9 = - 2x the square of - 14x + 24 2, (a + 2b-3) (a-2b + 3) = [a + (2b-3)] [a - (2b-3)] = the square of a - (2b-3)] = the square of a - (2b-3) = the square of a-4b + 12b-9 3, (2x-y) (3x-2y) + (Y-X) (2x-5y) = (6x's Square - 4xy-3xy + 2Y's Square) + (2xy-5y's Square - 2x's square + 5xy) = 6x's Square - 7xy + 2Y's square + 7xy-5y's Square - 2x's Square = 4x's Square - 3Y's Square 4, (2x-1) (2x + 1) (x's second power + X + 1) this one should be quartic,

If {X-1} = 2, find the value of X,
It'd better be within an hour. I have to hand it in tomorrow. It's this year's

If the brace is an absolute value, it should be as follows:
X-1 = 2 or X-1 = - 2
So: x = 3 or x = - 1

The function f (x) = X3 + AX2 + BX + C, where a, B and C are real numbers. When a2-3b < 0, f (x) is ()
A. Increasing function B. decreasing function C. constant D. is neither increasing function nor decreasing function

If f ′ (x) = 3x2 + 2aX + B, where △ = 4a2-12b ＜ 0, f ′ (x) ＞ 0, then f (x) is an increasing function

It is related to factorization
How does (1 + x2 & sup2;) X1 - (1 + X1 & sup2;) x2 change into (x1-x2) (1-x1x2) form? I can't see how···

The original formula = X1 + (x2) & sup2; x1-x2 - (x1) & sup2; x2
=(x1-x2)-x1x2(x1-x2)
=(x1-x2)(1-x1x2)

According to the following conditions, the vertex coordinates of the image are (- 3, - 2) and pass through points (1,2)
The image intersects the x-axis at points m (- 5,0), n (1,0), and the ordinate of the vertex is 3

There are three ways to find the analytic expression of quadratic function
1. Half of the general formula is y = a ^ 2 + BX + C [need three coordinates through the quadratic function]
2. The intersection formula y = a (x-x1) (x-x2) [requires the intersection of the quadratic function and the X axis and any coordinate passing through the function]
3. Vertex formula y = a (X-H) ^ 2 + k
1）
Let the quadratic function be the vertex formula y = a (X-H) ^ 2 + K
Then the vertex coordinates are (h, K)
∵ the vertex coordinates of the image are (- 3, - 2)
∴h=-3 k=-2
∴y=a(x+3)^2-2
∵ this quadratic function passes through (1,2)
Substituting the coordinate into the analytic expression to get a = 1 / 4
2)
Let the quadratic function be the intersection y = a (x-x1) (x-x2)
Then the two intersections of x-axis and X-axis are X1 and X2 respectively
From the meaning of the title, we get X1 = - 2, X2 = 1
∴y=a(x+2)(x-1)
The symmetry axis of this quadratic function is (x1 + x2) / 2 = (- 2 + 1) / 2 = - 1 / 2
∵ its vertex ordinate is 3
The vertex coordinates are (- 1 / 2,3)
Substituting the coordinates into the analytical formula, we get a = - 3 / 4
The analytic expression of this quadratic function is y = - 3 / 4 (x + 2) (x-1)
The solution is y = (- 3 / 4) x ^ 2 - 3 / 4x + 3 / 2

X²-8X-20=0

X²-8X-20=0
(x+2)(x-10)=0
So x = - 2 or x = 10

The vertex coordinates of the square of parabola y = X-2 (B + 2) x + B are on the coordinate axis, and the value of B is calculated

Y=(x-(b+2))^2-4b-4
Vertex coordinates (B + 2, - 4b-4)
X-axis, - 4b-4 = 0, B = - 1
Y-axis, B + 2 = 0, B = - 2

Encounter and pursuit in primary school
1. A truck drives from place a to place B at the speed of 30km / h. one hour after starting, a car also drives from place a to place B at the speed of 50km / h. it arrives at place B half an hour earlier than the truck to find the distance between a and B
2. On the road, there is a bus with a body length of 15 meters running from east to west at a speed of 18 kilometers per hour. On one side of the road, there are two young people, a and B, who are practicing long-distance running. A runs from east to west, B runs from west to East. At one moment, the car catches up with a, and leaves a after 6 seconds. Half a minute later, the car meets the oncoming B, and leaves B after 2 seconds, How many seconds later will a and B meet?

1. If the car runs x hours, then the truck runs x + 1 hour, 50x = 30x + 30 * 1 + 30 * 0.5x = 2.2550 * 2.25 = 112.5km2, 18000 / 3600 = 5m, 5-15 / 6 = 2.5m, 15 / 2-5 = 2.5m (5 + 2.5) * 30 = 225m, 225-2.5 * 3 (30 + 2) - 2.5 * 2 = 140m, 140 / (2.5 + 2.5) = 28 seconds

Find the trajectory equation of the moving point where the distance of point a (1,1) meets the distance of x-axis
RTRTRTRTR

(x-1) ^ 2 + (Y-1) ^ 2 = y ^ 2 simplify yourself