24÷2930×（78+134-1112-12）

24÷2930×（78+134-1112-12）

24÷2930×（78+134-1112-12）=24÷2930×（258-1112-12）=24÷2930×（11724-12）=24÷2930×1524=24×3029×2924=24×2924×3029=29×3029=30．

The calculation is simple by using the law of operation
79+199+75
=
=
=
The first plus sign becomes a multiply sign

79X199+5
=79X199+79-4
=79X200-4
=15800-4
=15796

How to calculate 2 × 74 out of 73 with a simple method?

2 / 73 × 74
= 2 of 73 × (73 + 1)
= 2 × 73 of 73 + 2 × 1 of 73
= 2 + 2 / 73
= 2 and 2 / 73

It is known that y = 1 is the solution of the equation 2-3 / 1 x (M-Y) = 2Y, and the solution of the equation about X is MX (x-3) - 2 = MX (2x-5)

Take y into the original equation, find m, take m into the following equation, and find X

What is the quotient of the product of 3 / 6 and 2 / 3 minus 3 / 2 and dividing it by 3 / 5?

(6 + 3 / 5 × 2 / 3-2 + 3 / 5) △ 3 + 3 / 5
=(33/5×2/3-13/5)÷18/5
=(22/5-13/5)×5/18
=9/5×5/18
=1 / 2 (1 / 2)

The length, width and height of a cuboid wooden box without cover are 8.2 decimeters, 5.2 decimeters and 4.1 decimeters respectively. It is known that the thickness of the board is 1 cm, and what is the volume of the box

(8.2-0.2)×（5.2-0.2）×（4.1-0.1）
=8×5×4
=160 square decimeters

The first question, a number divided by 11 remainder 1, divided by 13 remainder 3, divided by 17 remainder 7, find out the unknown number

This number + 10 can be divided by 11, 13 and 17, so this number + 10 = 11 * 13 * 17
This number = 2421
At least, my friends upstairs also checked the calculation. The calculation formulas are all there. Obviously, it's more than 10

It is known that each item of the equal ratio sequence {an} is a positive number, Sn is the sum of the first n items, and a1 + A5 = 34, A2 · A4 = 64. Find the common ratio Q and Sn of {an}

Because the sequence {an} is an equal ratio sequence, so A2 · A4 = A1 · A5 = 64, and because a1 + A5 = 34, so A1 and A5 are the two roots of the equation x2-34x + 64 = 0, the solution is A1 = 2, A5 = 32, or A1 = 32, A5 = 2, from an > 0, when A1 = 2, A5 = 32, Q4 = a5a1 = 16, q = 2, Sn = 2 (1 − 2n) 1 − 2 = 2n + 1-2

One by one in three plus three by one in five plus five by one in seven What is 97 times one in 99

One by one in three plus three by one in five plus five by one in seven 97 times 1 / 99 = 1 / 2 × (1-1 / 3) + 1 / 2 × (1 / 3-1 / 5) + 1 / 2 × (1 / 5-1 / 7) + +1/2×(1/97-1/99)=1/2×(1-1/3+1/3-1/5+1/5-1/7+…… +1/97-1/99)=1/2×(1-1/99)=1/2×98/99=49/99...

(5a-3b) - 3 (a-2b) + 7 (3b + 2a)

(5a-3b)-3(a^2-2b)+7(3b+2a)
=5a-3b-3a^2+6b+21b+14a
=19a+24b-3a^2