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1-21-2513-8-2 find the inverse of this matrix 1 -2 1 -2 5 1 3-8-2 find the inverse of this matrix
answer:
-2 -12 -7
-1 -5 -3
1 2 1
1. A store will increase the purchase price of a certain VCD by 35% and then put out an advertisement of 10% off to reward customers with 50 yuan taxi fare. As a result, each VCD will make a profit of 208 yuan. Suppose the purchase price of each super VCD is x yuan, and try to make an equation according to the meaning of the question
2. The number of people in group A is twice that of group B. eight people are transferred from group A to group B. This is the number of people left in group A, which is just more than half of what group B knows now. Let's set X people in group B and try to make the equation according to the meaning of the question
3. If the equation (2a + 1) x & sup2; + BX + C = 0 is a linear equation of one variable with respect to x, then the letter coefficients a, B and C satisfy ()
4. If the 2 | m | - 5 power-4m = 0 of (M-3) x is a one variable linear equation about X, find the value of M & sup2; - 2m + 1 / m
5. There are 272 people working in department a and 196 people working in department B. if we want to make the number of people working in department B equal to one third of the number of people working in department a, we should transfer x people from department B to department a, and try to make the equation according to the meaning of the question
6. In order to promote the sale of a calculator, a toy store offers a discount of no more than 10 calculators at a time, 38 yuan for each calculator, more than 10 calculators, and 2 yuan for each calculator. Ask Mr. Li for 812 yuan, and set up a total of X calculators. Try to list the equation according to the meaning of the question
7. A, B, C and D work together to process a batch of parts. The number of parts processed by a is 1 / 2 of that processed by the other three people, that processed by B is 1 / 3 of that processed by the other three people, and that processed by C is 1 / 4 of that processed by the other three people, which is just one less than that processed by D. how many parts are there in total
The process of writing is good, the more points are added!
1.0.9 * 1.35x-50-x = 208 or 90 * x * (1 + 0.35) - 50-x = 208
2.2x-8-(x+8)/2=3
2A + 1 = 0, B is not equal to 0, C belongs to R
2 | m | - 5 = 1, (M-3) is not equal to 0, then M = - 3, M & sup2; - 2m + 1 / M = 44 / 3
5.272+x=3(196-x)
6.380+(x-10)*36=812,x=22
7. If there are x, then a processes X / 3, B processes X / 4 and C processes X / 5
The equation of x-x / 3-x / 4-x / 5 is given
X-X/3-X/4-X/5＝X/5+1
Let four people process a, B, C and D each
Sequence equation 2A = B + C + D
3b=a+c+d,
4c=a+b+d
d=c+1
You can choose me
In {an}, A1 = 3, an = 96, Sn = 189, then n = ()
A. 6B. 8C. 10D. 12
Let the common ratio of the sequence {an} be Q. from the meaning of the title, we can get an = A1 · QN-1, that is, 96 = 3 · QN-1. From the reduction, we can get QN-1 = 32. ① Sn = A1 (1 − QN) 1 − q = 3 (1 − QN) 1 − q = 189. From the reduction, we can get 1 − QN1 − q = 63. ② from the combination, we can get q = 2, n = 6, so we choose a
A reservoir is equipped with a water inlet pipe and a drainage pipe. The water can be fully stored in 12 minutes by opening the water inlet pipe alone, and the water can be discharged in 18 minutes by opening the water discharge pipe alone. There is no water in the reservoir. The two pipes are opened for 6 minutes at the same time, and there is 70 cubic meters of water. The size of the reservoir depends on the formula
70÷[(1/12-1/18)×6]
=70÷1/6
=420 M3
As shown in the figure, the cross section of a reservoir dam is an isosceles trapezoid with a crest width of 6 meters and a dam height of 10 meters. The slope of slope AB is 1:2 (AR: BR). Now, if the crest width and slope gradient are unchanged, how much earthwork is needed to reinforce a 50 meter long dam
∵ in RT △ ABR, the slope of slope AB is 1:2, ar = 10, ∵ br = 20m, ∵ trapezoid ABCD is isosceles trapezoid, then BC = 2Br + ad = 46m, ∵ s trapezoid ABCD = (AD + BC) × ar △ 2 = 260m2, ∵ the slope of AB has no change before and after the transformation, and eh ⊥ BC is made at point h through point E. according to the title meaning, eh = 10 + 2 = 12M, ∵ pH = 2eh = 24m, the bottom length of trapezoid after the transformation is 2 × 24 + 6 = 54m The area of trapezoid is (54 + 6) × 12 △ 2 = 360 square meters. After the transformation, the extra area is s trapezoid epcf-s trapezoid ABCD = 360-260 = 100 square meters, so the required earthwork is 100 × 50 = 5000 cubic meters. A: 5000 cubic meters
Add the operation symbol and bracket in the appropriate position to make the equation hold
5 5 5 5 5 5 5 =1 1 2 3 4 5 6 7 8 9 0=10
(5 -5)x 5x 5x 5+ 5/ 5 =1 1+ 2+ 3+ 4 +5 x6 x7 x8x 9x 0=10
Let a and B be square matrices of order n, we know that the determinant of B is not equal to 0, A-E is invertible and the inverse matrix of (A-E) = (B-E) is transposed,
As shown in the figure, it can be deduced from the condition that a is the product of two invertible matrices, so a is invertible
When he was doing an addition math problem, because he left out the number 0 in one digit of an addend, the result was 54 less than the correct answer. How much is the addend
The correct number should be 10 times less than 0, that is, 9 times less than 0
The result is 54 less than the answer
So the number less 0 is 6
The addend is 60
Let the determinant a of n-order square matrix A = 0 and the adjoint matrix A * ≠ 0, then rank (a)=
n-1
Because R (a) must be less than n
A * is a matrix composed of n-1 subformulas, which is not zero
It shows that a ratio can take at least one n-1 subformula which is not zero
So r (a) = n-1
The number of 3.6 is 12.6, which is more than 45% of a number? (solve with equation) 2. The sum of a and B is 12. A is 13 of B. what are the numbers a and B?
(1) Let this number be X. according to the meaning of the question, we get 45% x + 3.6 = 12.6 & nbsp; & nbsp; 0.45X = 12.6-3.6 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 9 △ 0.45 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 20 A: this number is 20. (2) 12 △ 1 + 13) = 12 × 34 = 912-9 = 3 A: number a is 3, number B is 9
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