Solve equation 0.3x2 (square of x) - 4x + 15 = 55

Solve equation 0.3x2 (square of x) - 4x + 15 = 55

0.3x^2-4x+15=55
3x^2-40x-400=0
(3x+20)(x-20)=0
x1=-20/3,x2=20

Given that the square of x plus the square of y plus 2x-6y + 10 = 0, then x + y

The square of x plus the square of y plus 2x-6y + 10 = 0, that is: (x + 1) ^ 2 + (Y-3) ^ 2 = 0, so: x = - 1, y = 3
So: x + y = 2

Xsquare - 6x + 2 / 8, xsquare + 1 / X-6, 12 + x-xsquare 3-x
In particular, xsquare - 6x + 8, xsquare + X-6, 12 + x-xsquare

X squared - 6x + 8
=x²-2×3x+9-9+8
=（x-3）²-1
=（x-3-1）（x-3+1）
=（x-4）（x-2）
X square + X-6
=（x-2）（x+3）
12 + x-x square
=（4-x）（3+x）

A + B + C is equal to 2 A-B + C is equal to 20 4 / 6A + 2 / 3B + C is equal to 9 / 1A + 3 / 1b + C

Form a ternary linear equation system: a + B + C = 21, A-B + C = 20, 2, 6a / 4 + 3B + C / 2 = A / 9 + B + C / 9, 3, 2, 2-1, B = -- 9, substituting B = - 9 into 1, a + B-9 = 24, a-b-9 = 20, 5, 4, 4 + 5, a = 20, substituting a = 20, B = -- 9 into 1, C = -- 9, so 3 in the equation a = 20, B = -- 9, C = -- 9

The speed of the bus is x km / h, and the speed of the truck is 70 km / h. The two cars start from city a to city B at the same time. After driving for 5 hours, the bus just arrives
When the train has not yet arrived, the truck is several kilometers away from the city. If the truck is 100 kilometers away from the city, the speed of the bus is () km / h

5x-350 90

How much is one plus five seventh?

12/7

A truck and a motorcycle leave from a and B at the same time. The two vehicles meet for the first time at a distance of 60 km from a on the way. Then the two vehicles continue to move forward. When the truck arrives at B and the motorcycle arrives at a, they both return immediately. The two vehicles meet for the second time at a distance of 30 km from B on the way. What is the distance between a and B?

The total distance taken by two cars when they meet twice is three times that of a and B. suppose the total distance is x, then the equation is: (x + 30) + (X-60) × 3 = 3x4x-150 = 3x, x = 150; a: the distance between a and B is 150 km

When a student removed the denominator of the equation 2x-1 = x + A-2,
When a student solves the equation 2x-1 = x + A-2, the - 2 on the right side of the equation is not multiplied by 3. The solution of the equation is x = 2, and the value of a is the same as the original solution of the equation

A = 3 original solution x = 9 / 5

Given that a > 0, b > 0, and three points a (1,1), B (a, 0), C (0, b) are collinear, then the minimum value of a + B is______ ．

∵ a > 0, b > 0, and three points a (1, 1), B (a, 0), C (0, b) are collinear, then AB = λ · & nbsp; AC, i.e. (A-1, - 1) = λ (- 1, B-1), ∵ A-1 = - λ, - 1 = λ (B-1), a = 1 - λ > 0, B = 1-1, λ > 0, ∵ λ < 1 and 1 λ < 1, so there is λ < 0, - λ > 0. ∵ a + B = 2 + (- λ) + - 1 λ) ≥ 4, if and only if - λ = - 1 λ, i.e. & nbsp; When λ = - 1, the equal sign holds, so the answer is 4

For a decimal, you only need to read a zero. When Minmin was writing, she forgot to write the decimal point. As a result, it turned out to be 20408
() or ()

20.408
two thousand and forty point eight