The function y = xcosx SiNx is an increasing function () A. （π2，3π2）B. （π，2π）C. （ 3π2，5π2）D. （ 2π，3π）

The function y = xcosx SiNx is an increasing function () A. （π2，3π2）B. （π，2π）C. （ 3π2，5π2）D. （ 2π，3π）

Y '= cosx xsinx cosx = - xsinx to make the derivative positive, we only need X and SiNx symbols are always opposite. By analyzing the four options, we know that option B meets the conditions, so we should choose B

Matlab, the original function of partial differential function
P (R, t) is a function of R, t
Satisfy the following conditions: & ᦉ 8706; P / & ᦉ 8706; R + & ᦉ 8706; P / & ᦉ 8706; t = 0
p(r,0)=0
p(,t)=0
The primitive function p (R, t)

p(,t)=0
What is the position of X?

3 / 4 + 5 / 6 =?, 2 / 3-1 / 4 =
5 of 7-7 =?, 1 of 2 + 2 of 3 =?, 6 - (3 of 4-2 of 5) =?

Solution
3 / 4 + 5 / 6
=9 out of 12 + 10 out of 12
=19 out of 12
2 / 3-1 / 4
=8 / 12-3 / 12
=5 out of 12
4 / 5 + 1 / 15 + 3 / 10
=24 out of 30 + 2 out of 30 + 9 out of 30
=35 out of 30
=7 out of 6
7-5 / 7
=49 / 7-5 / 7
=44 out of 7
1 / 2 + 2 / 3
=3 / 6 + 4 / 6
=7 out of 6
6 - (3 / 4-2 / 5)
=6 - (15 / 20-8 / 20)
=6-7 / 20
=120-7 out of 20
=113 out of 20

If the parabola y = x2 + KX + 1 intersects y = x2-x-k and there is an intersection on the X axis, then the value of K is ()
A. 0B. 2C. -1D. 14

∵ the parabola y = x2 + KX + 1 intersects with y = x2-x-k, there is an intersection on the X axis, ∵ x2 + KX + 1 = x2-x-k, (K + 1) x = - k-1, x = - 1, substitute x = - 1, y = 0 into the analytic formula y = x2-x-k, 1 - (- 1) - k = 0, k = 2, so select: B

If the sum of 17 consecutive integers is 306, then the sum of the 17 consecutive integers immediately after the 17 integers is equal to 306______ ．

The sum of 17 consecutive integers is 306, then the sum of the following 17 consecutive integers is 306 + 17 × 17 = 595

The factorization result of polynomial X & # 178; y + Y & # 178; X & # 178; + X & # 178; z-2xyz + X & # 178; y is
The last X and y are Z and y

x²y＋y²x²＋x²z－2xyz＋x²y
=xy(x+xy+xz-2z+x)
=xy(2x+xy+xz-2z)

Simple calculation of 128 * 25-28 * 25

128*25-28*25
=（128-28）*25
=100*25
=2500

Ax ^ 2 + BX ^ 2-cx ^ 2 + A + B-C double cross factorization

ax" + bx" - cx" + a + b - c
= ax" + a + bx" + b - cx" - c
= a( x" + 1 ) + b( x" + 1 ) - c( x" + 1 )
= ( x" + 1 )( a + b - c )

What is negative 1.25 + (- 3 / 4) equal to (- 3 / 8 of 4) + 6.375 equal to (- 60) * (- 3 / 5 plus 5 / 6 minus 17 / 30) equal to?
And 3 minus (1 + x) equals 2x, x equals? 2 minus 1 / 5 minus x equals x, x equals? This is the equation

-1.25+（-3/4）
=-1.25-0.75
=-2
-4-3/8+6.375
=-4-0.375+6.375
=2
(-60)×（-3/5+5/6-17/30 ）
=（-60）×【（-3×6+5×5-17）/ 30】
=（-60）×（-10/30 ）
=20
Understand, please adopt in time!

After three cubes of the same size are put together into a cuboid, the surface area is reduced by 144 square centimeters. What is the surface area of this cuboid?
Come on`
Clean and tidy. Expressed in a column

The answer is 504 square centimeters
After three cubes are put together into a cuboid, a total of four faces are reduced, and the area of these four faces is 144 square centimeters. In this way, the area of each face of the cube can be calculated: 144 △ 4 = 36 square centimeters. Then subtract the reduced 144 square centimeters from the sum of the surface areas of the cube: 36 × 6 × 3-144 = 504 square centimeters