How to solve the equation with 3 + X + 18-x = 30?

How to solve the equation with 3 + X + 18-x = 30?

X-x = 30-3-18 (transposition) because x-x = 0, the equation has no solution

An annular iron sheet has an outer circumference of 18.84 decimeters and an inner radius of 1. How many square decimeters is the area of the annular iron sheet?
Don't just answer,

Hello
The radius of the outer circle is: 18.84 △ 3.14 △ 2 = 3 decimeters
So the area of the ring = the area of the outer circle - the area of the inner circle
therefore
The area is: 3.14 × 3-178; - 3.14 × 1.5-178; = 21.195 square decimeters
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Simple calculation of 0.4 times 1.25 times 8 times 2.5

0.4×1.25×8×2.5
=(0.4×2.5)×(1.25×8)
=1×10
=10

As shown in the figure, the side length of equilateral triangle ABC is 6, ad is the middle line on the side of BC, M is the moving point on ad, e is the point on AC, if AE = 2, then (EM + cm) &#;
The minimum value of is?

BM = cm, EM + cm = EM + BM, when e, m and B are in a straight line, (EM + cm) & # 178; minimum
Connecting EB, EB ^ 2 = 6 ^ 2 + 2 ^ 2-2 * 2 * 6cos 60 ° = 36 + 4-24 / 2 = 28
The minimum value of (EM + cm) &# is 28

If a = (A1, A2), B = (B1, B2), a vector product is defined: ab = (A1B1, a2b2),
Given that M = (2,1 / 2), n = (π / 3,0), and point P (x, y) moves on the image of function y = SiNx, point Q moves on the image of function y = f (x), and point P and point Q satisfy vector OQ = m, vector OP + N, then the maximum a and minimum positive period T of function y = f (x) are A2, π B2, 4 π C1 / 2, π D1 / 2, 4 π C1 / 2, respectively

Let the coordinates of point p be (a, Sina) and Q be (x, y). According to the condition vector OQ = vector m · vector OP + vector n, we obtain x = 2A + π / 3 -------- deformation -------- a = (x - π / 3) / 2 y = 0.5sina. Substituting a = (x - π / 3) / 2 into the formula y = 0.5sina, we obtain the maximum value of y = 1 / 2 * (sin (x / 2 - π / 6)) sin

How to prove that the area of three triangles connected by three vertices from the triangle center of gravity is equal

As shown in the figure, O is the center of gravity,
First of all, the area of a triangle is 1 / 2 of the product of the edge and the distance from the edge to the vertex
2. The point is the intersection of the center lines of the triangle
3. Because point O is the common vertex of triangle 1 and 2, the height from point O to ab should be the height of AF and BF of triangle 1 and 2, that is, the height of the bottom edge of triangle on the same vertex is the same
It is proved that since AF = BF, S1 = S2 (the height on the bottom edge is the same), S1 + S4 + S5 = S2 + S3 + S6; so S3 + S6 = S4 + S5
Because AE = EC, so S4 = S5, S1 + S2 = S3 + S6 can also be obtained
So: S1 + S2 = S3 + S6 = S4 + S5

The first power of 2 = 2, the second power of 2 = 4, the third power of 2 = 8, the fourth power of 2 = 16
Observation and induction: what is the rule of the last digit of the nth power of 2 (n is a positive integer)?
Can you name the last number of 2 to the power of 2012?

Observation and induction: the nth power of 2 (n is a positive integer)
The law of the last digit of the number is: press 2, 4, 8, 6, 2, 4, 8, 6 Cycle on;
∵2012÷4＝503
The last digit of 2012 power of 2 is the same as that of 4 power of 2, which is 6

Calculation: x ^ 3M + 2n △ x ^ m + n=

The original formula = x ^ [(3m + 2n) - (M + n)]
=x^(2m+n)

Let a, B, C be three real numbers, and 1 + A + 1 / B + 1 / C = 1 (a + B + C) = 1. It is proved that at least one of a, B, C is equal to 1

1 / A + 1 / B + 1 / C = 1 general score: (AB + BC + Ca) / ABC = 1 ｛ AB + BC + Ca = ABC ｛ AB + BC + Ca ABC = 0 = AB + BC + ca-a-b-c-abc + A + B + C = AB + BC + ca-a-b-c-abc + 1 = 1-A + (AB + BC + ca-b-c-abc) = 1-A + [b (A-1) + C (A-1) - BC (A-1)] = (1-A) (1-b-c + BC) = (1-A) (1-B) (1-C) = 0 ｛ a

There is a triangle space. Gardeners want to divide it into three equal triangles to plant different plants
And the edge of each piece of land should not be too long. Please help them to complete this task. Draw a schematic diagram and write the method

Is this an equilateral triangle
Are you satisfied with the above answers?