Mathematics problem known y = x square + ax + B, when x = 1, y = 2; when x = - 1, y = 4, when x = 1 / 2, y value

Mathematics problem known y = x square + ax + B, when x = 1, y = 2; when x = - 1, y = 4, when x = 1 / 2, y value

Take x = 1, y = 2 to get a + B = 1
If x = - 1, y = 4, then - A + B = 3
The sum of the two formulas gives B = 2, so a = - 1
So the equation is y = x ^ 2-x + 2
When x = 1 / 2, y = 7 / 4

A mathematical problem is known that a line y = AX-2 passes through points (- 3, - 8) and (1 / 2, b), then a =, B=
Don't ask for the answer directly. Please explain it for me. Thank you

∵ the line y = AX-2 passes through the point (- 3, - 8)
∴-8=-3a-2
a=2
(1 / 2, b)
∴b=2x1/2-2=-1
therefore
a=2,b=-1

Let f (x) = cos (2x - π / 6) (1) find the minimum positive period of function f (x) and the set of values of X when the maximum value is obtained. (2) find the equation of symmetry axis of function f (x) image

（1）T=2π/2=π
When 2x - π / 6 = 2K π, f (x) has a maximum
So x = k π + π / 12 (k is an integer) is the set of values of X when the maximum value is obtained
(2) Let 2x - π / 6 = k π (k is an integer)
X = k π / 2 + π / 12 (k is an integer)
So the equation of symmetry axis of F (x) image is x = k π / 2 + π / 12 (k is an integer)

In known plane rectangular coordinate system, point O is the origin, a (- 3, - 4) B (5, - 12)
If the vector OC = OA + ob, calculate the OC coordinate
Why vector OC ≠ vector ob

OA=（-3,-4）,OB=（5,-12）
∴OA＋OB=（-3+5,-4-12）=（2,-16）
It can be seen from the plane coordinates that OB and OC are different in size and direction, so the vector OC ≠ the vector ob

If 4x cubic - 2x quadratic + k - 2x can be divisible by 2x, then the value of constant k is ()
A.1 B.- 1 C.2 D.o

D

In the cube abcd-a1b1c1d1 with edge length 1, points e, F and G are the midpoint of dd1, BD and BB1 respectively. Find the length of CE

Given that point E is the midpoint of dd1, we can get: de = (1 / 2) dd1 = 1 / 2;
In RT △ CDE, CD ⊥ De, CD = 1, de = 1 / 2,
According to Pythagorean theorem, CE = √ (CD ^ 2 + de ^ 2) = √ 5 / 2

There are 20 idioms with two numbers, 20 idioms with animal names and 20 idioms with human organ names

Light head and heavy feet, finger pointing, sad face, bright eyes, gaping, tongue tied, whispering, yellow and thin, quick eyes, high eyes and low hands, high head and high chest, dexterity, rubbing hands, shoulder to shoulder, fear, hearing, dexterity, seven hands, seven mouths, five viscera, light car Jun

Given that the circumference angle of a 3 cm long string is 135 degrees, then the diameter of the circle is 135 degrees___ ．

As shown in the figure, ∵ AB = 3cm, ∵ ACB = 135 °, ∵ ADB = 45 °, ∵ AOB = 90 °, ∵ AOB is isosceles right triangle, ∵ 2oa2 = 9, the solution is OA = 322, ∵ 2oa = 32

4 + 5x = 15. 4

5.4+5x=15.4
Solution 5x = 15.4-5.4
5x=10
x=2

The height of a parallelogram is 6cm, the bottom is 16cm, and the diagonal is 12cm. Find the perimeter

（6+16）* 2 = 22 *2 = 44