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If E1 and E2 are a group of bases in the plane, then the following four groups of vectors can be used as bases of plane vectors A、e1-e2,e2-e1B、2e1-e2,e1-1/2e2C、2e2-3e1,6e1-4e2D、e1+e2,e1-e2
Choose D
Because E1 and E2 are a group of bases in the plane, E1 and E2 are not collinear
Therefore, E1 + E2 and E1-E2 are not collinear, which can be used as the basis of plane vector
1 / 3 x + 2 + X-1 / 3 + 2 times 1 / 2 + 38 = x solves the equation
1 / 3 x + 2 + X-1 / 3 + 2 times 1 / 2-1 + 38 = x
4X / 3 + 119 / 3 = x
x=119
[5x - (4x-9)] / (4x-9) = 2 / 3 solution equation
［5x－（4x－9）］／（4x－9）＝2／3
（x+9）／（4x－9）＝2／3
Double 3 (4x-9)
3x+27=8x-18
5x=45
x=9
The number of solutions of the equation | log2 (x + 1) | - 2x + 1 = 0 is
There is only one focus
The original formula can be reduced to | log2 (x + 1) | = 2x-1
You just need to correctly draw the image of F (x) = | log2 (x + 10) | and f (x) = 2x-1, and then use the special value verification method to find that there is a real number solution x = 1
Electronic calculator is generally composed of () and switches, (), () and ()
Internal circuit of keyboard on power supply display screen
If the radii of two circles passing through point C (3,4) and tangent to both x-axis and y-axis are R1 and R2 respectively, then r1r2=______ ．
Let the coordinates of the center of the circle be (a, a), then the radius r = a, and the equation of the circle is (x-a) 2 + (Y-A) 2 = A2, and C (3, 4) on this circle, substitute the coordinates of C into (3-A) 2 + (4-A) 2 = A2, and sort out: a2-14a + 25 = 0, ∵ R1, R2 are two solutions of a2-14a + 25 = 0, ∵ r1r2 = 25 The case is: 25
In the expansion of binomial (a-b) ^ 7, which term has the largest coefficient
Item 5
Given a = 2 × 3 × 5, B = 2 × 5 × 7, then the greatest common factor of a and B is______ ．
Given a = 2 × 3 × 5, B = 2 × 5 × 7, then the greatest common factor of a and B is 2 × 5 = 10
If 2 is a root of quadratic equation x2 + BX + 2 = 0, then the value of constant B is______ ．
Substituting 2 into the equation is: 4 + 2B + 2 = 02B = - 6B = - 3
Using dichotomy to find the approximate value (accuracy 0.1) of equation 0.8 ^ X - 1 = LNX in the interval (0,1)
RT, you don't need the process
0.8
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