If the solutions of the equations x + 2Y = B, X-Y = 9-3a are a pair of identical numbers, find the value of A Is a = 3?

If the solutions of the equations x + 2Y = B, X-Y = 9-3a are a pair of identical numbers, find the value of A Is a = 3?

If the solution is a pair of the same numbers, then x = y
Substituting X-Y = 9-3a
x-x=9-3a
9-3a=0
a=3

You can put the nine numbers 1-9 into the following formula to make the equation hold
(one question mark, one number)
There are three numbers. Their average is 48. The average of two of the three numbers is 56. What's the third number

The answer to the first question mark is no, I used the program to verify, no answer
The calculation method of the second question is 48 × 3-56 × 2 = 32

Given that the asymptote equation of hyperbola is y = + - X and the distance between two vertices is 2, then the standard equation of hyperbola is y = + - X

The asymptote equation of hyperbola is y = + - x, that is, B / a = 1, B = a
The distance between two vertices is 2, that is, 2A = 2, a = 1
That is, a = b = 1
The hyperbolic equation is x ^ 2-y ^ 2 = 1 or Y ^ 2-x ^ 2 = 1

59. What about circles?
PEP mathematics book

01. A circle has numerous radii 02. A circle has numerous diameters 03. In the same circle, the diameter is twice the radius 04. In the same circle, the radius is half of the diameter 05. All line segments in a circle have the longest diameter 06. There are numerous symmetrical axes 07. A point in the center of a circle is called the center of a circle, which is generally represented by the letter "O". 08

Quadratic function y = AX2 + BX + C (A0, please judge the sign of a, B, C, and b2-2ac > 5A2

Because over (- 1,0), A-B + C = 0
So C = B-A, then 4A + 2B + C = 3B + 3A > 0
That is b > - A
So b > 0, A0
Then C = B-A is brought into b2-2ac
=b2-2a(b-a)
=b2-2ab+2a2
So we only discuss whether b2-2ab is greater than 3a2
Because b2-2ab = B (b-2a)
b> - A, b-2a > - 3a, and B is a positive number
So the original formula is greater than 3a2

3,4, - 6,10. Add, subtract, multiply and divide each number once. The result is 24. There are three formulas

3×[4+10+(-6)]=24
10-4-3×(-6)=24
4-(-6)÷3×10=24
{[(10-6)/4]+3}!=4!=4×3×2×1=24
4×3×√(10-6)=4×3×2=24

The equation x-ax + 1 = 0 has two real roots

From the question: A ^ 2-4 > 0
So a > 2 or a

Why is trigonometric function periodic?

Trigonometric functions have periodicity, which is related to the properties of angles: for example, a person faces north, when he rotates 90 ° to the right, he will face east. If he faces north, when he rotates 90 ° to the right, he will continue to rotate 360 ° to face east

If the length of the line segment obtained by y = 2 is π 8, then the value of F (π 12) is ()
A. 33B. 1C. -1D. -3

∵ function f (x) = Tan ω x (ω > 0), the length of the line segment obtained from the two adjacent sectional lines y = 2 is π 8, so the period of the function is π ω = π 8, ∵ ω = 8, f (x) = Tan 8x, ∵ f (π 12) = Tan 2, π 3 = - Tan π 3 = - 3, so D

All answers to the first volume of mathematics exercise book of grade 6 [People's education press]

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