2X percent equals 13 percent of 40 and 0.75x-5x percent equals 17 and 1.2 percent

2x％＝13/40
0.2x＝13/40
x＝13/40÷0.2
x＝1.625
75x-5x% = 17 1 / 2
0.75x－0.05x＝35/2
0.7x＝35/2
x＝35/2÷0.7
x=25
Wang Cai!

Let a straight line with a slope of 2 intersect an ellipse x ^ 2 / 16 + y ^ 2 / 4 = 1 at P1 and P2, and find the trajectory equation of the midpoint of the chord p1p2

Let P1 (x1, Y1) P2 (X2, Y2)
The midpoint is (x, y)
That is, X1 + x2 = 2x, Y1 + y2 = 2Y and (y1-y2) / (x1-x2) = 2
Elliptic equation x & # 178 / 16 + Y & # 178 / 4 = 1
That is X & # 178; + 4Y & # 178; = 16
Substituting p1p2 coordinates
x1²+4y1²=1
x2²+4y2²=1
Subtraction of two formulas
x1²-x2²+4(y1²-y2²)=0
(x1+x2)(x1-x2)+4(y1+y2)(y1-y2)=0
(x1+x2)+4(y1+y2)(y1-y2)/(x1-x2)=0
2x+8y*2=0
X + 8y = 0 is the trajectory

On mechanical digital computer
1. Who spent several years inventing the first mechanical digital computer in the world?
2. Who developed which machine laid the foundation for the development of modern computer design ideas?
No, just the first question,

1. In 1847, Charles Babbage, a computer pioneer and British mathematician, began to design a mechanical difference machine. The overall design took two years. This machine can complete 31 bit precision operations and print the results on paper, so it is generally considered to be the first mechanical computer in the world
2. Charles Babbage, an Englishman, developed business extension and analyzer, which laid the foundation for the development of modern computer design
100% right~

(-8)^2012*(-1/8)^2013

(-8)^2012*(-1/8)^2013
=-(8)^2012*(1/8)^2013
=-(8)^2012*(1/8)^2012*1/8
=-(8x1/8)^2012x1/8
=-1x1/8
=-1/8

Urgent: let d be an interval in the domain of the function y = f (x). If there exists x0 ∈ d such that f (x0) = - x0, then x0 is said to be a sub fixed point of F (x)
If f (x) = ax2-3x-a+
52 there is a fixed point in the interval [1,4]. Find the value range of constant A. why is the value of a (- ∞,
12) Why can we get (- ∞, 0) and X can only get [1,4]
The function is: ax2-3x-a + 5 / 2, the value is (- ∞, 1 / 2), the semicolon cannot be displayed

Please distinguish a and X correctly. A can take all real numbers, and the interval refers to X

Given a = 2009, B = 2010, C = 2011, find the square of a + the square of B + the square of c-ab-bc-ac

a^2+b^2+c^2-ab-bc-ac
=(a^2-ab)+(b^2-bc)+(c^2-ca)
=a(a-b)+b(b-c)+c(c-a)
=-2009-2010+2011×2
=（2011-2009）+（2011-2010）
=2+1
=3

In the plane rectangular coordinate system, translate the point P (M + 2, 2m + 4) to the right by 1 unit length to get the point P '(4, 6), then the value of M is______ ．

∵ point P (M + 2, 2m + 4), ∵ right translation 1 unit length can get p '(M + 2 + 1, 2m + 4), ∵ p' (4, 6), ∵ m + 2 + 1 = 4, 2m + 4 = 6, the solution is: M = 1, so the answer is: 1

One third to one ninth = x is faster than 4

1/3÷1／9=x/4
3=x/4
x=12

Given vector group A1, A2 It is proved that vector group B1 = A1, B2 = a1 + A2 ，br=a1+a2+… +AR is also linearly independent

Suppose there is a set of real numbers K1 So that k1b1 + +Krbr = 0, namely & nbsp; & nbsp; k1a1 + K2 (a1 + A2) + +kr（a1+… +ar）=（k1+… +kr）a1+（k2+… +kr）a2+… +Krar = 0. Because vector group A1, A2 So K1 + +kr＝0… KR − 1 + Kr = 0kr = 0. Because of the coefficient matrix of the equations 101… 1 ⋮⋮⋱⋮ 0001. = 1 ≠ 0, so from the necessary and sufficient conditions for the existence of nonzero solutions of homogeneous linear equations, K1 = K2 = =So vector group B1, B2 It is linear independent

2X percent equals 13 percent of 40 and 0.75x-5x percent equals 17 and 1.2 percent