Factorization of (m ^ 2 + 8m + 15) (m ^ 2 + 8m + 7) + 15

Factorization of (m ^ 2 + 8m + 15) (m ^ 2 + 8m + 7) + 15

Let m ^ 2 + 8m + 15 = t
Then the original formula = t (T-8) + 15
=t²-8t+15
=（t-3）（t-5）
=（m^2+8m+15-3）（m^2+8m+15-5）
=（m^2+8m+12）（m^2+8m+10）
=（m+2）（m+6）（m^2+8m+10）

Factorization m ^ 2-8m + 7

(M-1)(m-7)

It is calculated by simple method: 57.6 × 1.6 + 28.8 × 36.8-14.4 × 80.5

57.6×1.6+28.8×36.8-14.4×80=57.6×1.6+28.8×2×18.4-14.4×4×20=57.6×1.6+57.6×18.4-57.6×20=57.6×（1.6+18.4-20）=0

Simple calculation of 1 / 2 + 3 / 4 + 7 / 8 + 15 / 16

1/2+3/4+7/8+15/16
=1-1/2+1-1/4+1-1/8+1-1/16
=4-(1/2+1/4+1/8+1/16)
=4-(1-1/16)
=3 and 1 / 16

If X1 and X2 are two real roots of the quadratic equation x ^ 2 + (A-2) x + 1 = 0, find the solution of (1 + ax1 + X1 ^ 2) (1 + AX2 + x2 ^ 2)

The original formula can be reduced to 2x1 * 2x2 = 4x1x2 = 4

Use 20cm long and 8cm wide tiles to paste a square wall. If the square wall is just made of complete tiles, what is the minimum side length of the square wall? How many such tiles do you need?

(1) 20 = 2 × 2 × 5, 8 = 2 × 2 × 2, so the minimum common multiple of 20 and 8 is 2 × 2 × 5 × 2 = 40, that is, the minimum side length of the square wall is 40 cm; (2) the area of the wall: 40 × 40 = 1600 (square cm), the area of the ceramic tile: 20 × 8 = 160 (square cm), the required ceramic tile for pasting the wall: 1600 △ 160 = 10 (pieces), a: the minimum side length of the square wall is 40 cm; it needs 10 cm Only one such tile can be pasted

What is the meaning of Kirchhoff's law of magnetic circuit

It's similar to Kirchhoff's law of circuit. Just look at the picture

How can the inverse function of y = arcsinx be x = siny
 

The inverse function is to use y to express x, that is to say, the result is the same as the original function, but the expression is different. You can substitute x equal to two-thirds of the root sign

As shown in the figure on the right, use three small cubes with 1cm edge length to form a rectangle. What's its surface area?

The surface area of cuboid = (length × width + length × height + width × height) × 2, that is, (1 × 1 + 1 × 3 + 1 × 3) × 2 = 14 (cm ^ 2)

How can I use my brain to do it?

Take it apart first, and then find the value of the number