1959+3910−5.221959−62750+5.22÷(1993×0.41995×0.5+1.61995)．

1959+3910−5.221959−62750+5.22÷(1993×0.41995×0.5+1.61995)．

1959+3910−5.221959−62750+5.22÷(1993×0.41995×0.5+1.61995)，=1959−1.321959−1.32÷1993×0.4+0.81995×0.5，=1÷0.4×(1993+2)1995×0.5，=1÷45，=54．

How to calculate d = a B C A ^ 2 B ^ 2 C ^ 2 B + C C + a a a + B for the absent row Vandermonde determinant

R3 + R1, line 3 (a + B + C)
a b c
a^2 b^2 c^2
1 1 1
Exchange line (2 times)
1 1 1
a b c
a^2 b^2 c^2
This is the Vandermonde determinant
Determinant = (a + B + C) (B-A) (C-A) (C-B)

What is (51 / 10F + 17 / 38) × 19 / 51F?

(51 / 10 + 17 / 38) × 19 / 51
=51/10x19/51+17/38x19/51
=10/19+1/6
=60/114+19/114
=79/114

Biochemistry, about PI
The Pi of amino carboxyl amino acids is neutral because the dissociation degree of - COOH and NH2 is the same?

The ionization degree of amino group and carboxyl group in amino acid molecule is different. Even for neutral amino acid, the ionization degree of the two groups is also different. The ionization degree of carboxyl group is slightly higher than that of amino group. The isoelectric point of neutral amino acid is 5.6.3

How much is 9 out of 10 times 9 out of 10?

81 out of 100,

If x is the first quadrant angle, which of SiNx / 2, cosx / 2, tan2 / X is positive
Why!

Let x = θ + 2K π (0

A simple way to divide 8 / 9 by 4 and multiply 3 / 4

Hello
8/9÷4x3/4
=(8/9x3/4)÷4
=2/3÷4
=1/6
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The line L passes through the point m (1,1), intersects the ellipse x ` 2 + 4Y ` 2 = 16, and points P and Q. given that the abscissa of the midpoint of the line PQ is 1 / 2, the equation of the line is obtained

Let L: y = K (x-1) + 1,
By substituting x ` 2 + 4Y ` 2 = 16, we get
(1+4k^2)x^2+8k(1-k)x+4(1-k)^2-16=0,
Let P (x1, Y1), q (X2, Y2), then
x1+x2=8k(k-1)/(1+4k^2),
The abscissa of PQ is 4K (k-1) / (1 + 4K ^ 2) = 1 / 2,
∴8k^2-8k=1+4k^2,4k^2-8k-1=0,
K = 1 Soil (√ 5) / 2,
The equation of L is y = [1 + (√ 5) / 2] x - (√ 5) / 2, or y = [1 - (√ 5) / 2] x + (√ 5) / 2

Solution equation: 4 / 2X-4 = 3x + 5 / 3x-6-1 / 3 (specific process)

4 / (2X-4) = (3x + 5) / (3x-6) - 1 / 3 denominator decomposable factor
4 / [2 (X-2)] = (3x + 5) / [3 (X-2)] - 1 / 3 the simplest common denominator is 6 (X-2), and both sides of the equation multiply the simplest common denominator 6 (X-2)
12 = 2 (3x + 5) - 2 (X-2) without brackets
12 = 6x + 10-2x + 4
6x-2x = 12-10-4 merge
4x=-2
x=-1/2
Test: substitute x = - 1 / 2 into the simplest common denominator, 6 (X-2) = - 15 ≠ 0
X = - 1 / 2 is the solution of the original equation

Given that the real numbers 4, m and 9 form an equal ratio sequence, then the eccentricity of the conic curve X & # 178 / / M + Y & # 178; = 1 is
A root 30 / 6 C root 30 / 6 or root 7 C root 7

Root 30 / 6 or root 7