Decomposition common factor 1. A (x + y) - B (x + y) 2. M (a-b) - n (B-A)

Decomposition common factor 1. A (x + y) - B (x + y) 2. M (a-b) - n (B-A)

1.a(x+y)-b(x+y)=(x+y)(a-b)
2.m(a-b)-n(b-a)=m(a-b)+n(a-b)=(a-b)(m+n)

2,7,17,37,77,( ),( )

Answer: 2,7,17,37,77, (157), (317)
law:
17=7+5×2
37=17+10×2
77=37+20×2
157=77+40×2
317=157+80×2
.
do you understand?

1.What can you group do ____ the talent show.
A.to
B.in
C.at
D.for
2.Do you like a guitar or a piano?_______
A.Yes,I like a guitar
B.No,I like a piano
C.A guitar or a piano
D.A piano
3.They're all famous______
A.swim
B.swimer
C.swimers
D.swimmers

1D is
2. D choose questions to answer directly
3. D swimmers, in the plural

Fold the square ABCD so that vertex a coincides with point m on the edge of CD. The crease intersects ad at e, BC at F, and BC at G after folding
If M is any point on the edge of CD, let AB = 2A, ask whether the perimeter of triangle CGM is related to the position of point m? If so, use the algebraic expression of length x containing DM to express the perimeter of triangle CGM

In △ EMD, let de be y, then EM = AE = 2a-y, using Pythagorean theorem, y = (4a ^ 2-x ^ 2) / 4A
△EMD∽△CGM,CG=4ax/（2a+x）MG=(4a^2+x^2)/(2a+x)
Perimeter = 2a-x + 4ax / (2a + x) + (4a ^ 2 + x ^ 2) / (2a + x)
=4A. So it has nothing to do with X

2.25 × 4.8 + 77.5 × 0.48

2.25×4.8+77.5×0.48=2.25×4.8+7.75×4.8=（2.25+7.75）×4.8=10×4.8=48．

Use arithmetic (to explain)
My mother gave a photo album to Amin. Amin put all his photos into the album. If there are 3 photos on each page, the last two pages are empty. If there are 5 photos on each page, the last nine pages are empty. How many photos does Amin have, and how many pages does the album have?

The number of photos needed is 9 * 5-2 * 3 = 39, the number of album pages = 39 / (5-3) = 19.5, but the number of pages can only be an integer, so the number of album pages = 20, the number of photos = (20-2) * 3 = 54, and the number of photos = (20-9) * 5 = 55

In trapezoidal ABCD, angle a = 90 degrees, BH is the vertical bisector of CD, BH = AB = 2 root sign 3. Find the area of trapezoidal ABCD
Trapezoid ABCD is a right angle trapezoid, which can be connected to BD

Let d be de ⊥ BC ∵ s △ BCD = 1 / 2BC × de = 1 / 2CD × BH and ∵ BH = AB = de ∵ BC = CD ∵ BH is the vertical bisector of CD ≁ BC = BD = CD ∵ BCD is an equilateral triangle ∵ de = H = AB = 2 √ 3 ∵ BC = CD = BD = 4 ∵ CE = 1 / 2CD = 2, ad = be = 2 ∵ s trapezoid ABCD = 1 / 2 ×

If a man-made satellite circulates around the earth at a uniform speed and its orbit radius is 13 times of that of the moon around the earth, the cycle of the satellite is about ()
A. 1-4 days B. 4-8 days C. 8-16 days D. 16-20 days

According to gmmr2 = MR (2 π T) 2, t = 4 π 2r3gm, then the period ratio of the satellite to the moon is t star, t month = 127 = 133. The period of the moon around the earth is about 27 days, then the period of the satellite is t star ﹥ 5.77 days

Test your IQ application questions`
A 25.12-meter-long rope just goes around the trunk four times. What's the cross-sectional area of the trunk?

Radius: 25.12 ／ 4 ／ 3.14 ／ 2 = 1m
The cross-sectional area of the trunk is 3.14 × 1 × 1 = 3.14 square meters

The perimeter of a rectangle is 130 cm. If the length is increased by 27 and the width is decreased by 13, the perimeter of the new rectangle remains unchanged. Then the area of the original rectangle is______ Square centimeter

According to the stem analysis, we can get: because the perimeter of the new rectangle is unchanged, so the length × 27 = width × 13, then the ratio of length to width is 7:6, 7 + 6 = 13, so the length of the original rectangle is: (130 △ 2) × 713 = 35 (CM), the width is: (130 △ 2) × 613 = 30 (CM), and the area is: 30 × 35 = 1050 (square centimeter)