| Tìm a biết 1/ a + b – c = 18 với b = 10 ; c = -9 2/ 2a – 3b + c = 0 với b = -2 ; c = 4 3/ 3a – b – 2c = 2 với b = 6 ; c = -1 4/ 12 – a + b + 5c = -1 với b = -7 ; c = 5 5/ 1 – 2b + c – 3a = -9 với b = -3 ; c = -7 |
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
20 tháng 3 2023
1: Áp dụng tính chất của DTSBN, ta được:
\(\dfrac{x}{7}=\dfrac{y}{13}=\dfrac{x-y}{7-13}=\dfrac{42}{-6}=-7\)
=>x=-48; y=-91
2: x/y=3/4
=>4x=3y
=>4x-3y=0
mà 2x+y=10
nên x=3 và y=4
3: =>7x-3y=0 và x-y=-24
=>x=18 và y=42
4: =>7x-5y=0 và x+y=24
=>x=10 và y=14
B
Tìm các số a,b,c biết
1,-3x^3.(2ax^2-bx+c)=-6x^5+9x^4-3x^3
2,(ax+b)(x^2-cx+2)=x^3+x^2-2
Giúp mình với ạ
0
TM
14 tháng 1
Bài 3.
\(\left\{{}\begin{matrix}a\left(a+b+c\right)=-\dfrac{1}{24}\left(1\right)\\c\left(a+b+c\right)=-\dfrac{1}{72}\left(2\right)\\b\left(a+b+c\right)=\dfrac{1}{16}\left(3\right)\end{matrix}\right.\)
Dễ thấy \(a,b,c\ne0\Rightarrow a+b+c\ne0\)
Chia (1) cho (2), ta được \(\dfrac{a}{c}=3\Rightarrow a=3c\left(4\right)\)
Chia (2) cho (3) ta được: \(\dfrac{c}{b}=-\dfrac{2}{9}\Rightarrow b=-\dfrac{9}{2}c\left(5\right)\).
Thay (4), (5) vào (2), ta được: \(-\dfrac{1}{2}c^2=-\dfrac{1}{72}\)
\(\Rightarrow c=\pm\dfrac{1}{6}\).
Với \(c=\dfrac{1}{6}\Rightarrow\left\{{}\begin{matrix}a=3c=\dfrac{1}{2}\\b=-\dfrac{9}{2}c=-\dfrac{3}{4}\end{matrix}\right.\)
Với \(c=-\dfrac{1}{6}\Rightarrow\left\{{}\begin{matrix}a=3c=-\dfrac{1}{2}\\b=-\dfrac{9}{2}c=\dfrac{3}{4}\end{matrix}\right.\)
Vậy: \(\left(a;b;c\right)=\left\{\left(\dfrac{1}{2};-\dfrac{3}{4};\dfrac{1}{6}\right);\left(-\dfrac{1}{2};\dfrac{3}{4};-\dfrac{1}{6}\right)\right\}\)
23 tháng 3 2020
1, a+b-c = 18 với b=10 ; c=-9
Với b=10 ; c=-9 ta có:
a+b-c = a+10-(-9)
=> a+10-(-9) = 18
<=> a+10+9=18
<=> a=18-10-9
<=> a=-1
Vậy a = -1
2, 2a - 3b + c = 0 với b = -2 ; c = 4
Với b=-2 ; c=4 ta có:
2a - 3b + c = 2a - [3.(-2)] + 4
=> 2a - [3.(-2)] + 4 = 0
<=> 2a - (-6) + 4 = 0
<=> 2a + 6 + 4 = 0
<=> 2a = 0-6-4
<=> 2a = -10
<=> a = (-10) : 2
<=> a = -5
Vậy a = -5
k mình nha
14 tháng 3 2020
1) Thay b= 10; c = -9 vào biểu thức, ta có:
\(a+10-\left(-9\right)=18\)
\(a=18-10-9\)
\(a=-1\)
2) Thay b = -2; c= 4 vào biểu thức ta có:
\(2a-3.\left(-2\right)+4=0\)
\(2a+10=0\)
\(2a=-10\)
\(a=-5\)
3) Thay b = 6; c= -1 vào biểu thức ta có:
\(3a-6-2.\left(-1\right)=2\)
\(3a-4=2\)
\(3a=6\)
\(a=2\)
b) Thay b = -7; c= 5 vào biểu thức ta có:
\(12-a+\left(-7\right)+5.5=-1\)
\(12-a+18=-1\)
\(12-a=-19\)
\(a=-7\)
5) Thay b = -3; c= -7 vào biểu thức ta có:
\(1-2.\left(-3\right)+\left(-7\right)-3a=-9\)
\(-3a=-9\)
\(a=3\)
hok tốt!!
NN
6 tháng 7 2021
1.1. Mức độ nhận biết
1. Maryam wanted___________ the mosque on Hang Luoc Street.
A. to visit B. visit C. visited D. visiting
2. Do you enjoy___________other countries?
A. to visit B. visit C. visited D. visiting
3. People must___________something to protect our environment.
A. doing B. did C. do D. to do
4. The examiner asked him___________many questions about his hobby.
A- to answer B- answering C- answered D- answers
5. Let’s ___________ Hoa in the hospital to cheer her up.
A. to visit B. visitedC. visitingD. visit
6. What about ___________ to HCM city for our holiday?
A. to goB. goingC. goD. goes
7.We decided_________a house with a swimming pool.
A. buys B. to buy C. bought D. to buying
8. Why don’t we ___________ out and have some fun this weekend?
A. goingB. goC. to goD. goes
9. They are not old enough___________drive a car to school.
A. drive B. to drive C. drove D. driving
10. My dad doesn’t mind ___________ my mom from work every day.
A. pick up B. picked up C. picking up D. to pick up
11. What should you___________if you face this problem?
A. do B. doing C. to do D. does
12. Wearing uniforms encourages students___________proud of their school because the uniforms bear their schools’ name.
A. to be B. be C. being D. been
13. Tom avoids ___________his lessons as long as possible.
A. study B. studying C. to study D. studied
14. I finally finished___________at 7p.m, and served dinner.
A. cooking B. being cooked C. to cook D. to be cooked
15. Let me ___________ from you soon.
A. to hear B. hear C. hearing D. heard
16. Ha loves ___________ with her mum on Sunday
A. go shop B.to go shop C. going shoppingD.going shop
17. My students enjoy ___________ English very much.
A. learn B. learning C. to learn D. learnt
18. Please let Tom ___________with you.
A. go B. going C. to go D. goes
19. Haven't you finished___________ the answer?
A. write B. writing C. how to write D. them to write
20. That actor is very good at ___________ the voices of other people. |
| |||||||
A. imitate | B. imitated | C. imitating | D. to imitate |
| ||||
21. We can _______ funds for street children by collecting old newspapers and magazines. |
| |||||||
A. to raise | B. raise | C. raising | D. raised | |||||
22. Do you have a pen? I want ___________ in this application form. |
| |||||||
A. filling | B. to fill | C. filled | D. fill | |||||
23. How about___________out for luch?
A. go B. going C. to go D. goes
24. It’s noteasy___________pass the final exam without working hard.
A. passing B. pass C. to pass D. passed
25. The teacher told her students ___________talking.
A- stop B- stopped C- to stop D- stopping
26. You cant stop me from _____ what I want.
A. doing B. do C. to do D. that I do
27. Everyone dislikes _______ early on Sundays. | |||
A. gets up | B. getting up | C. togetting up | D. get up |
28. He tried to ______ my question.
A. answering B. to answer C. answer D. how to answer
29. There’s no point in him to do that.
A. persuade B. persuadingC. persuaded D. to persuade
30. Tom offered…………..Jane a ticket to the theater, but she refused to take it.
A. to give | B. give | C. giving | D. to be given |
KY
6 tháng 7 2021
1.1. Mức độ nhận biết
1. Maryam wanted___________ the mosque on Hang Luoc Street.
A. to visit B. visit C. visited D. visiting
2. Do you enjoy___________other countries?
A. to visit B. visit C. visited D. visiting
3. People must___________something to protect our environment.
A. doing B. did C. do D. to do
4. The examiner asked him___________many questions about his hobby.
A- to answer B- answering C- answered D- answers
5. Let’s ___________ Hoa in the hospital to cheer her up.
A. to visit B. visitedC. visitingD. visit
6. What about ___________ to HCM city for our holiday?
A. to goB. goingC. goD. goes
7.We decided_________a house with a swimming pool.
A. buys B. to buy C. bought D. to buying
8. Why don’t we ___________ out and have some fun this weekend?
A. goingB. goC. to goD. goes
9. They are not old enough___________drive a car to school.
A. drive B. to drive C. drove D. driving
10. My dad doesn’t mind ___________ my mom from work every day.
A. pick up B. picked up C. picking up D. to pick up
11. What should you___________if you face this problem?
A. do B. doing C. to do D. does
12. Wearing uniforms encourages students___________proud of their school because the uniforms bear their schools’ name.
A. to be B. be C. being D. been
13. Tom avoids ___________his lessons as long as possible.
A. study B. studying C. to study D. studied
14. I finally finished___________at 7p.m, and served dinner.
A. cooking B. being cooked C. to cook D. to be cooked
15. Let me ___________ from you soon.
A. to hear B. hear C. hearing D. heard
16. Ha loves ___________ with her mum on Sunday
A. go shop B.to go shop C. going shoppingD.going shop
17. My students enjoy ___________ English very much.
A. learn B. learning C. to learn D. learnt
18. Please let Tom ___________with you.
A. go B. going C. to go D. goes
19. Haven't you finished___________ the answer?
A. write B. writing C. how to write D. them to write
20. That actor is very good at ___________ the voices of other people. |
| |||||||
A. imitate | B. imitated | C. imitating | D. to imitate |
| ||||
21. We can _______ funds for street children by collecting old newspapers and magazines. |
| |||||||
A. to raise | B. raise | C. raising | D. raised | |||||
22. Do you have a pen? I want ___________ in this application form. |
| |||||||
A. filling | B. to fill | C. filled | D. fill | |||||
23. How about___________out for luch?
A. go B. going C. to go D. goes
24. It’s noteasy___________pass the final exam without working hard.
A. passing B. pass C. to pass D. passed
25. The teacher told her students ___________talking.
A- stop B- stopped C- to stop D- stopping
26. You cant stop me from _____ what I want.
A. doing B. do C. to do D. that I do
27. Everyone dislikes _______ early on Sundays. | |||
A. gets up | B. getting up | C. togetting up | D. get up |
28. He tried to ______ my question.
A. answering B. to answer C. answer D. how to answer
29. There’s no point in him to do that.
A. persuade B. persuadingC. persuaded D. to persuade
30. Tom offered…………..Jane a ticket to the theater, but she refused to take it.
A. to give | B. give | C. giving | D. to be given |
7 tháng 5 2021
Giải:
a) A=1718+1/1719+1
17A=1719+17/1719+1
17A=1719+1+16/1719+1
17A=1+16/1719+1
Tương tự:
B=1717+1/1718+1
17B=1718+17/1718+1
17B=1718+1+16/1718+1
17B=1+16/1718+1
Vì 16/1719+1<16/1718+1 nên 17A<17B
⇒A<B
b) A=108-2/108+2
A=108+2-4/108+2
A=1+-4/108+2
Tương tự:
B=108/108+4
B=108+4-4/108+1
B=1+-4/108+1
Vì -4/108+2>-4/108+1 nên A>B
c)A=2010+1/2010-1
A=2010-1+2/2010-1
A=1+2/2010-1
Tương tự:
B=2010-1/2010-3
B=2010-3+2/2010-3
B=1+2/2010-3
Vì 2/2010-3>2/2010-1 nên B>A
⇒A<B
Chúc bạn học tốt!
12 tháng 3 2023
17A=1719+1+16/1719+1
17A=1+16/1719+1
phần in nghiêng mình không hiểu lắm, bn giải thích cho mình được ko?
20 tháng 1 2020
thay số vào ta có
thôi bạn
nên cái này bạn
nên tự làm
9 tháng 4 2020
1) a + b - c = 18
a + 10 + 9 = 18
a + 10 = 18 - 9
a + 10 = 9
a = 9 - 10
a = -1
2) 2a - 3b + c = 0
2a - 3 .(-2) + 4 =0
2a + 6 +4 = 0
2a + 6 = 0 - 4
2a + 6 = -4
2a = -4 -6
2a = -10
a = -5
3) 3a - b - 2c = 2
3a - 6 - 2 .(-1) = 2
3a - 6 + 2 =2
3a - 6 = 2-2
3a = 6
a = 2
Tìm a biết
1/ a + b – c = 18 với b = 10 ; c = -9
Thay b=10;c=-9 vào a+b-c=18 ,ta được:
=> a+10-(-9)=18
a+10+9=18
a+10=18-9
a+10=7
a=7-10
a=-3
Vậy a=-3
2/ 2a – 3b + c = 0 với b = -2 ; c = 4
Thay b=-2;c=4 vào 2a-3b+c=0 ,ta được:
=> 2a-3.(-2)+4=0
2a+6+4=0
2a=0-4-6
2a=-10
a=-10:2
a=-5
Vậy a=-5
3/ 3a – b – 2c = 2 với b = 6 ; c = -1
Thay b=6;c=-1 vào 3a-b-2c=2 ,ta được:
=> 3a-6-2.(-1)=2
3a-6+2=2
3a-6=2-2
3a-6=0
3a=0+6
3a=6
a=6:3
a=2
Vậy a=2
4/ 12 – a + b + 5c = -1 với b = -7 ; c = 5
Thay b=-7;c=5 vào -a+b+5c=-1 ,ta được:
=> -a+(-7)+5.5=-1
-a-7+25=1
-a-7=1-25
-a-7=-24
-a=-24+7
-a=-17
=> a=17
Vậy a=17
5/ 1 – 2b + c – 3a = -9 với b = -3 ; c = -7
Thay b=-3;c=-7 vào 1-2b+c-3a=-9 ,ta được:
=> 1-2.(-3)+(-7)-3a=-9
1+6-7-3a=9
6-7-3a=9-1
6-7-3a=8
7-3a=6-8
7-3a=-2
3a=7-(-2)
3a=9
a=9:3
a=3
Vậy a=3