Given the quadratic function y = x ^ 2-x + a (a is greater than 0), when the independent variable x is m, the corresponding function value is less than 0, then the correct is () A. The function value of M-1 is less than 0, the function value of b.m-1 is greater than 0, and the function value of c.m-1 is equal to 0 D

Choose B
The function is a quadratic function with an opening upward, and it has two intersections with the X axis (obtained from the fact that when the independent variable x takes m, its corresponding function value is less than 0), and the sum of the two is X1 + x2 = 1, X1 * x2 = a
∴(x1-x2)^2=1-4a.
|x1-x2|=√(1-4a)
And ∵ a > 0,
∴1-4a

In a 5 × 5 square, put a white chess piece first, and then a black chess piece. The two chess pieces are not in the same row or column______ There are two different ways to put it

25 × 16 = 400 (species); a: there are 400 different ways to put them

When a changes, the function of Y with respect to x, y = (x-a) square + a square - 2a-1, changes the vertex position of the image
(1) When a = 0, find out the length (2) a of the line segment of the parabola on the x-axis, and what is the longest line segment of the parabola on the x-axis

1) As a result, we are going to want to be the x-y-178, and THE-1 x-178; and THE-1 x-178; and the-1-1 = 1-1 (x-11-1) = 22) y = (x-a) \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\a + 4) = √ [- 4 (A-1) &# 178; + 8] therefore

Given a = A2 + b2-c2, B = - 4a2 + 2B2 + 3c2, a + B + D = 0, what kind of polynomial is C

∵ a + B + D = 0 should be a + B + C = 0
∴a2+b2-c2+（-4a2+2b2+3c2）+C=0
Simplification: - 3A & # 178; + 3B & # 178; + 2C & # 178; + C = 0
∴C=3a²-3b²-2c²

ABCD-CDC=ABC A=?B=?C=?D=?

A=1 B=0 C=9 D=8

For a right angle trapezoid, the ratio of the upper bottom to the lower bottom is 3:5. If the upper bottom is increased by 7 cm and the lower bottom by 1 cm, the area of the trapezoid can be calculated

Let the upper bottom length be x and the lower bottom length be y
X/Y＝3/5
X＝3Y/5 （1）
X+7＝Y+1 （2）
Substituting (1) into (2)
3Y/5+7＝Y+1
Y＝15
Substituting y = 15 into (1)
X＝9
Trapezoid height = square side length = y + 1 = 15 + 1 = 16
Trapezoid area = (9 + 15) * 16 / 2 = 192 (cm2)

It is known that the three sides a, B and C of △ ABC satisfy B + C = 8, BC = a ^ 2-12a + 52

First, replace a ^ 2-12a + 52 with a complete square formula, and get BC = (a-6) ^ 2 + 16. Then substitute B + C = 8, and get B (8-b) = (a-6) ^ 2 + 16 8b-b2-16 = (a-6) 2. Finally, we get an equation with complete square formula on both sides, (B-4) 2 = (a-6) 2

Look at pictures and guess idioms

It's different and equal to each other. It's self-evident. It's worth mentioning. It's different and quick. It's incomparable. It's hard to laugh or cry. It's not the same inside and outside. It's not trivial. It's a mess. It's unnecessary. It's a fantasy. It's boundless. It's white and black. It's the head of the government

Given that X and y satisfy the condition that the square of x plus the square of y plus five fourths equals 2x plus y, find the value of XY divided by X + y

Formula > add 1 and 1 / 4x square - 2x (+ 1) + y square - Y (+ 1 / 4) + 5 / 4 = 1 + 1 / 4 on both sides of the equation, merge with complete square formula 〉 (x - 1) square + (Y - 1 / 2) square + 5 / 4 = 1 + 1 / 4 on both sides

How many centimeters should be drawn on a plan with a scale of 1:20000 for a bridge with an actual length of 1200 meters?
Use the equation to solve

I admit I'm embarrassed
1200M=120000CM
Let's draw x centimeters
1:20000=X:120000
20000X=120000×1
20000X÷20000=120000÷20000
X=6
A: 6cm