The two vehicles a and B run from a and B at the same time. The meeting point of the two vehicles is 8km away from the midpoint of a and B. It is known that the speed of vehicle a is 1.2 times that of vehicle B, so the distance between a and B can be calculated Solve the equation of first degree with one variable I always feel like less than a meeting time, if there is time can be calculated. 100 points reward!

Let the distance be (1 / 2x + 8) km for car a and (1 / 2x-8) km for car B. by calculating (1 / 2x + 8) / 1.2V = (1 / 2x-8) / V with equal time, we can get (1 / 2x + 8) / (1 / 2x-8) = 1.2/1 and get x = 176

Mathematics into the new curriculum
1、 If the square of (x + 2) plus the absolute value of Y + 3 = 0, then x + y =? To know that x is less than 0 and Y is greater than 0, then the absolute value of X + y is equal to? Known 2 is greater than X and X is less than 4, then the absolute value of X-2 + x-4 =? Known absolute value of x-3 plus the absolute value of Y + 2 / 3 = 0, then x =? Y =?
2、 Find the absolute value of X (process) x - 1 / 2 = 0, the absolute value of X-1 = 2

1、 If the absolute value of the square of (x + 2) plus y + 3 = 0, then x + y =?
x+2=0,y+3=0
We get x = - 2, y = - 3
So x + y = - 2 + (- 3) = - 5
If x is less than 0 and Y is greater than 0, then the absolute value of X + y is equal to? Y-x
If 2 is greater than X and X is less than 4, then the absolute value of X-2 + x-4 =? X-2 + 4-x = 2
2 < x < 4, so X-2 + x-4 = X-2 + 4-x = 2
Given the absolute value of x-3 plus the absolute value of 2 / 3 of y = 0, then x =? Y =?
x-3=0,y+2/3=0
We get x = 3, y = - 2 / 3
2、 Find x (process)
The absolute value of X - 1 / 2 = 0
︱x︱=1/2
x=±1/2
The absolute value of X-1 = 2
︱x-1︱=2
x-1=±2
X = 3 or x = - 1

New curriculum standard synchronous unit practice Mathematics Grade 7 Volume 1 20 page 21 answers 5 questions 9 questions

Specific topics and questions

There are three inner horn species of triangle, the most of them are_ Acute angle, at least_ Sharp angle, at most_ Right angles, at most_ An obtuse angle

3；2；1；1

If the length of three sides of a triangle is known to form an arithmetic sequence with one tolerance, and the maximum angle is twice the minimum angle, then the circumference of the triangle is?
I don't understand what's on Baidu

Let a triangle be three sided ABC and a = B + 1 = C + 2
a/sinA=c/sinC =＞ ( c+2)/(2sinCcosC)=c/sinC =＞ 2c cosC=c+2 .①
c²=a²+b²-2abcosC =＞ c²=(c+2)²+(c+1)²-2(c+2)(c+1)cosC .②
① (2) the solvable C-value of F equations
Then the perimeter of the triangle is 3C + 3

If the length of three sides of a triangle is known to form an arithmetic sequence with a tolerance of 1, and the minimum angle is twice that of the maximum foot, the length of three sides can be calculated

In the triangle ABC, the opposite sides of angles a, B and C are a, B and C respectively, and a, B and C form an arithmetic sequence in turn, and the maximum angle a is twice the minimum angle C. the sine theorem and cosine theorem are used to solve the problem. From the positive metaphysical theorem, we get Sina / a = sinc / C, that is, 2sinccosc / a = sinc / C ∧ COSC = A / 2C, and from the co metaphysical theorem, we get COSC = a ^ 2 + B

If the triangle ABC is similar to the triangle a'b'c ', the lengths of the three sides of the triangle ABC are root 2, root 6 and root 2 respectively, and the lengths of the two sides of the triangle a'b'c are root 1 and root 3 respectively, then the length of the third side of the triangle a'b'c' is -

Column ratio: √ 2 ∶ 1 = 2 ∶ the third side
The solution is: the third side = 2 / √ 2 = √ 2

Let ABC be the three sides of a triangle and prove that a / (B + C-A) + B / (a + C-B) + C / (a + B-C) > = 3

Let B + C-A = x, a + C-B = y, a + B-C = Z. then x > 0, Y > 0, z > 0. A = (y + Z) / 2, B = (Z + x) / 2, C = (x + y) / 2, a / (B + C-A) + B / (a + C-B) + C / (a + B-C) = (y + Z) / 2x + (Z + x) / 2Y + (x + y) / 2Z = (Y / x + X / y) / 2 + (Z / x + X / z) / 2 + (Y / Z + Z / Z + Z / y) / 2

It is known that triangle ABC is similar to triangle a'b'c ', and the ratio of three sides of ABC is 3:7:9. The maximum side length of triangle a'b'c' is 27cm. The perimeter of triangle a'b'c 'is calculated

27／9*（3+7+9）=57

In the isosceles triangle ABC, ab = AC = 17cm, BC = 30cm, the area of △ ABC=______ cm2．

Let ad ⊥ BC, ≁ AB = AC, ≁ d be the midpoint of BC, that is BD = DC = 15cm. In the right angle △ abd, ab = 17cm, BD = 15cm, ≁ ad = AB2 − BD2 = 8cm, ≁ ABC has an area of 12 × BC × ad, = 12 × 30 × 8cm2, = 120cm2