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15 tháng 10 2016
b/ Xác định điều kiện xác định ta có
\(\hept{\begin{cases}2-x^2+2x\ge0\\-7x-8\ge0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}1-\sqrt{3}\le x\le1+\sqrt{3}\\x\le\frac{-8}{7}\end{cases}}\)
=> Tập xác định của phương trình là tập rỗng nên phương trình vô nghiệm
15 tháng 10 2016
Cái đề đúng không thế cháu hình như bị vô nghiệm hết cả 2 bài luôn
NT
0
4 tháng 10 2016
Mình hướng dẫn nhé :)
- Phương trình \(\sqrt{x-2\sqrt{x}+1}=\sqrt{x}-1\Leftrightarrow\sqrt{\left(\sqrt{x}-1\right)^2}=\sqrt{x}-1\Leftrightarrow\left|\sqrt{x}-1\right|=\sqrt{x}-1\)
Xét trường hợp để tìm nghiệm nhé :)
- \(\sqrt{4x^2-4x+1}=1-2x\Leftrightarrow\sqrt{\left(2x-1\right)^2}=1-2x\Leftrightarrow\left|2x-1\right|=1-2x\)
- \(\sqrt{x+2\sqrt{x-1}}=3\Leftrightarrow\sqrt{\left(\sqrt{x-1}+1\right)^2}=3\Leftrightarrow\left|\sqrt{x-1}+1\right|=3\) (mình sửa lại đề)
- \(\sqrt{x^2-4}=\sqrt{x^2-2x}\Leftrightarrow\sqrt{\left(x-2\right)\left(x+2\right)}=\sqrt{x\left(x-2\right)}\Leftrightarrow\sqrt{x-2}\left(\sqrt{x+2}-\sqrt{x}\right)=0\)
- \(\sqrt{x^2+5}=x+1\). Tìm điều kiện xác định rồi bình phương hai vế.
19 tháng 7 2019
gợi ý nhé
a (=) 2x.( 4x2+1) = (3x+2). căn(3x+1) ( x>=-1/3)
đặt 2x =a
căn (3x+1) = b (b>=0)
ta có hpt sau a.(a2 +1)=b.(b2+1) (1)
3a-2b2= -2 (2)
giải (1) (=) a3 + a = b3 + b
(=) (a-b).(a2+ab+b2+1) = 0 =) a=b ( vì a2+ab+b2+1>0)
phần còn lại tự giải nhé
b (=) (x+1).(x2+2x+2)=(x+2) . căn(x+1) (x>=-1)
(=) căn (x+1) . [căn(x+1) . (x2+2x+2) -x-2] = 0
=) x=-1
hay căn(x+1) . (x2+2x+2) -x-2=0
cách 1 giải phổ thông ( chuyển vế rồi bình phương)
cách 2 đặt ẩn phụ và lập hệ
đặt căn(x+1)=a (a>=0)
=) a.[x(a2+1)+2] = a2+1 và a2 - x =1
tự giải nhé
c,tạm thời chưa nghĩ ra
HN
1
16 tháng 12 2017
đang vội nên mk làm tắt nha . đk x>=-5/4
\(\Leftrightarrow2\left(x+1\right)\)\(.\left[\left(x+2\right)-\sqrt{4x+5}\right]+2 \left(x+5\right)\sqrt{x+3}\left(\sqrt{x+3}-2\right)+\)\(2x^2+6x-8=0\)
\(\Leftrightarrow\frac{2\left(x+1\right)^2\left(x-1\right)}{x+2+\sqrt{4x+5}}+\frac{2\left(x+5\right)\left(x-1\right)\sqrt{x+3}}{\sqrt{x+3}+2}+2\left(x-1\right)\left(x+4\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left[\frac{2\left(x+1\right)^2}{x+2+\sqrt{4x+5}}+\frac{2\left(x+5\right)\sqrt{x+3}}{\sqrt{x+3}+2}+2\left(x+4\right)\right]=0\)
de thấy bt trong ngoặc dương suy ra x=1 là no
CT
8 tháng 12 2019
đặt đk
rồi bphuong 2 vế lên nha
c2: đặt x+5=t
thay vào pt
biểu diễn theo t
hok tốt
T
9 tháng 12 2019
ĐKXĐ:\(x\ge-5\)
Đặt \(\sqrt{x+5}=t\ge0\Rightarrow x+5=t^2\)
Ta có hệ: \(\hept{\begin{cases}x^2-4x-3=t\\x+5=t^2\end{cases}}\Leftrightarrow\hept{\begin{cases}\left(x-2\right)^2=t+7\\x-2=t^2-7\end{cases}}\)
Lấy pt trên cộng pt dưới, vế với vế:
\(\left(x-2\right)^2+\left(x-2\right)=t^2+t\)
\(\Leftrightarrow\left(x-t-2\right)\left(t+x-1\right)=0\)
...
P/s:Em ko chắc
2 tháng 10 2020
ĐK: \(2x+3\ge0\Rightarrow x\ge\frac{-3}{2}\)
Pt \(\Leftrightarrow x^2+4x+5-2\sqrt{2x+3}=0\)\(\Leftrightarrow x^2+2x+1+2x+3-2\sqrt{2x+3}+1=0\)
\(\Leftrightarrow\left(x+1\right)^2+\left(\sqrt{2+3}-1\right)^2=0\)\(\Leftrightarrow\hept{\begin{cases}x+1=0\\\sqrt{2x+3}-1=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=-1\left(tm\text{đ}k\right)\\2x+3=1\end{cases}}}\)
Vậy x=-1 là nghiệm của pt.
20 tháng 5 2018
Trung bình cộng của hai so bằng 135. Biết một trong hai số la 246. Tìm số kia
DL
25 tháng 7 2018
\(2x^2+2x+1=\sqrt{4x+1}\)
\(\left(2x^2+2x+1\right)^2=\left(\sqrt{4x+1}\right)^2\)
\(4x^4+8x^3+8x^2+4x+1=4x+1\)
\(\Leftrightarrow4x^4+8x^3+8x^2=0\)
\(\Leftrightarrow4x^2\left(x^2+2x+2\right)=0\)
\(\Leftrightarrow x=0\)
T
15 tháng 7 2019
Ko chắc đou:( Nhất là cái đk ý, phải xét đủ thứ cái ... nào là VT>=0 với bt trong căn >=0.. ko biết có nhầm lẫn hay ko nx!
ĐK: \(x\ge\sqrt{2}\)
PT <=> \(4x^2+3x-\frac{9}{2}=\sqrt{x^2-2}-\frac{1}{2}\)
\(\Leftrightarrow\left(4x-3\right)\left(x+\frac{3}{2}\right)=\frac{x^2-\left(\frac{3}{2}\right)^2}{\sqrt{x^2-2}+\frac{1}{2}}\)
\(\Leftrightarrow\left(x+\frac{3}{2}\right)\left(4x-3-\frac{x-\frac{3}{2}}{\sqrt{x^2-2}+\frac{1}{2}}\right)=0\)
Giải cái ngoặc to: \(4x-3-\frac{2x-3}{2\sqrt{x^2-2}+1}=0\Leftrightarrow\left(8x-6\right)\sqrt{x^2-2}+2x=0\)
Dễ thấy VT >0 với mọi \(x\ge\sqrt{2}\) do vậy cái ngoặc to vô nghiệm.
\(\Rightarrow x=-\frac{3}{2}\)
Of course she is right. Panties are more comfortable. Actually as a girl I don't have experience of men's boxers but few boys in my friend circle use panties and according to them that are more comfortable than their regular and bore boxers. One thing to keep in mind that use one size larger than your regular size , if you are using 90 or L size regularly then whenever you buy panty take 95 or XL in that way. Actually its told by one of my boy friend and its pracal also as woman inners are somewhat tight for men due to penis and testes.
As far as girls point of view concerned I think many men now using bikinis instead of frenchis. As bikinis provide more comfort to their private organs and provide some kind of pleasure and excitement as well .
Some of boys in my friend circle use panties. I had done their shopping with them on many occasions. My cousin sister's husband is also using bikinis since about last 6–7 years as regular innerwear and my she has no objection.
Basically its problem of thinking . We attach that small piece of cloth with gender ,if you see careful both men inners and women panties are very much similar in look only some design and fashion trends are introduced in panties to make them more attractive and sex appealing.
Only piece of cloth panty can't decide your gender. Its every one's individual matter what to wear and what not. As jeans, T shirts, sport wears, shoes, jerkins, sweat shirt and many more things are now common for boys and girls then why not panties? I think one should prefer his or her comfort rather than others opinion or objections.
Of course she is right. Panties are more comfortable. Actually as a girl I don't have experience of men's boxers but few boys in my friend circle use panties and according to them that are more comfortable than their regular and bore boxers. One thing to keep in mind that use one size larger than your regular size , if you are using 90 or L size regularly then whenever you buy panty take 95 or XL in that way. Actually its told by one of my boy friend and its pracal also as woman inners are somewhat tight for men due to penis and testes.
As far as girls point of view concerned I think many men now using bikinis instead of frenchis. As bikinis provide more comfort to their private organs and provide some kind of pleasure and excitement as well .
Some of boys in my friend circle use panties. I had done their shopping with them on many occasions. My cousin sister's husband is also using bikinis since about last 6–7 years as regular innerwear and my she has no objection.
Basically its problem of thinking . We attach that small piece of cloth with gender ,if you see careful both men inners and women panties are very much similar in look only some design and fashion trends are introduced in panties to make them more attractive and sex appealing.
Only piece of cloth panty can't decide your gender. Its every one's individual matter what to wear and what not. As jeans, T shirts, sport wears, shoes, jerkins, sweat shirt and many more things are now common for boys and girls then why not panties? I think one should prefer his or her comfort rather than others opinion or objections.