Đáp án:
Giải thích các bước giải:
3c
`C=|x+1|+|2-x|`
ta có
`|x+1|+|2-x|>=|x+1+2-x|=3`
dấu = xảy ra khi
`(x+1)(2-x)>=0`
`<=>(x+1)(x-2)<=0`
vì `x+1>x-2`
`=>{x+1>=0`
`{x-2<=0`
`=>{x>=-1`
`{x<=2`
`=>-1<=x<=2`
2b
`|x-5|-x=3`
`=>|x-5|=3+x`
`=>x-5=x+3`
hoặc `x-5=-3-x`
`=>0=8`(vô lý)
hoặc `2x=2`
`=>x=1`
c
`2x-1≠2x+3`
`=>|2x-1|≠|2x+3|`
=>ko có giá trị nào của x thỏa mãn đề bà
dấu ≠ là khác nha
$b) x=1$
$c) x=\dfrac{-1}{2}$
b) Xét $|x-5|-x=3$
$⇒x-5-x=3$
$⇒x-x=3+5$
$⇒0=8$ (Loại)
Xét $|x-5|-x=3$
$⇒|x-5|=3+x$
$⇒x-5=x+3$
$⇒x-5=-3-x$
$⇒x=2-x$
$⇒2x=2$
$⇒x=1$
Vậy $x=1$
c) Xét $|2x-1|=|2x+3|$
$⇒2x-1=2x+3$
$⇒2x-1+1=2x+3+1$
$⇒2x=2x+4$
$⇒x=x+2$(Vô lí)
Xét $2x-1=-2x-3$
$⇒2x+2x-1=-2x-3+2x$
$⇒4x-1=-3$
$⇒4x=-3+1$
$⇒4x=-2$
$⇒x=\dfrac{-1}{2}$
Lớp 6A có 60 học sinh chia làm 3 loại:giỏi , khá , trung bình.Số học sinh giỏi bằng 1/5 số học sinh khá,số học sinh trung bình bằng 2/3 tổng số học sinh khá và giỏi.Tính số học sinh giỏi,khá và trung bình
em hãy viết 1 đoạn văn nêu suy nghĩ của em về đời sống của nhân dân lúc bấy giờ trong câu chuyện "chuyện cũ trong phủ chúa trịnh " ?đv văn khoảng 8 dòng
phân tích đa thức sau thành nhân tử: 16x^8+1 ai xong trước cho hay nhất
.................................
mình đang từ lớp 8 lên lớp 9 nên chx hiểu dạng này lắm, ai giải chi tiết giúp mình với
Câu 1: Execise 1: Read the passage carefully and choose the correct answer. Jean spent her first few years in Hooper and her family moved to Otsego early in her life. She was only ten when her father died unexpectedly, leaving her mother to raise and support their family alone. Her mother soon went to work outside the home to provide for the family, and Jean, being one of the oldest, had to help care for her younger siblings. Although she had much responsibility at home, Jean thoroughly enjoyed school and was an excellent student. She went on to graduate 10th in her class at Otsego High School in 1953. While still in high school, Jean met a young man named Charles "Chuck" Holly, at a dance in Alamo; and they were quite taken with each other. Over the next few years, their love for each other blossomed and they were married on February 24, 1953, while Jean was still in school. At the time, Chuck was serving his country in the military, and had come home on leave to marry his sweetheart. Unfortunately, shortly thereafter, he was sent overseas to serve in Korea for the next fifteen months. Upon his discharge, the couple settled into married life together in the Plainwell, Otsego area. To help make ends meet, Jean went to work at the collection bureau in Kalamazoo for a while, before taking a job at the cheese company in Otsego. In 1964, Chuck and Jean were overjoyed with the birth of their son, Chuck, who brought great joy into their lives. Jean remembered how her mother was always gone so much working after her father died and she did not want that for her son, so she left her job to devote herself to the role of a mother. After Jean's father passed away, her mother used to _______. A. work outside the home B. be a housewife C. support the family alone D. work as a secretary Câu 2:Which is not referred to Jean? A. She was a responsible girl. B. She often did well at school C She never helped her mother with household chores. D. She went to high school.
cho a,b,c là 3 số thực đôi một khác nhau thỏa mãn a/b-c+a/c-a+c/a-b=0. CM:a/(b-c)^2+a/(c-a)^2+c/(a-b)^2
mn giúp mình với nha mình đang cần gấp. Cho mình cảm ơn trước
cho a,+b+c=9 và a^2+b^2+c^2=53. tính ab+bc+ca.
Complete the conversations, using the correct form of the word(s) supplied and adding any other worlda needed 12: A: We'd better go to the bank this morning. B: Can't we go .... (late) ? A: No. They shut ... (early/ here) they do at home.
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