Tính nhanh
(-167) x 83 + 167 x (-17) -33
tìm x
( x mũ 2 +1 ) x ( 49- x mũ 2)= 0
( 3-x) x (8-x)>0
(x+2)x (x-3) <0
x+X nhân Y +x=9
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\(\left(x-\frac{1}{2}\right)^2=0\)
\(\Leftrightarrow\left(x-\frac{1}{2}\right)^2=0^2\)
\(\Leftrightarrow x-\frac{1}{2}=0\)
\(\Leftrightarrow x=\frac{1}{2}\)
Vậy x = 1/2
\(\left(x-2\right)^2=1\)
\(\Leftrightarrow\left(x-2\right)^2=1^2\)
\(\Leftrightarrow x-2=1\)
\(\Leftrightarrow\orbr{\begin{cases}x-2=1\\x-2=-1\end{cases}\Leftrightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}}\)
Vậy x = 3 hoặc x = 1
\(\left(2x-1\right)^3=-8\)
\(\Leftrightarrow\left(2x-1\right)^3=\left(-2\right)^3\)
\(\Leftrightarrow2x-1=-2\)
<=> 2x = -1
<=> x = -0,5
Vậy x = -0,5
\(\left(x-\frac{1}{2}\right)^2=0\)
\(x-\frac{1}{2}=0\)
\(x=\frac{1}{2}\)
\(\left(x-2\right)^2=1\)
\(\Leftrightarrow\orbr{\begin{cases}x-2=1\\x-2=-1\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1+2\\x=-1+2\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}\)
Vậy\(x\in\left\{3;1\right\}\)
\(\left(2x-1\right)^3=-8\)
\(\left(2x-1\right)^3=\left(-2\right)^3\)
\(2x-1=-2\)
\(2x=\left(-2\right)+1\)
\(2x=-1\)
\(x=-1\times2\)
\(x=-2\)
\(x\left(\frac{1}{2}\right)^2=\frac{1}{16}\)
\(x\left(\frac{1}{2}\right)^2=\left(\frac{1}{4}\right)^2\)
\(\Leftrightarrow\orbr{\begin{cases}x\frac{1}{2}=\frac{1}{4}\\x\frac{1}{2}=-\frac{1}{4}\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{4}:\frac{1}{2}\\x=-\frac{1}{4}:\frac{1}{2}\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{1}{2}\\x=-\frac{1}{2}\end{cases}}}\)
1, \(3x\left(x-7\right)+2x-14=0\)
\(\Rightarrow3x\left(x-7\right)+2\left(x-7\right)=0\)
\(\Rightarrow\left(x-7\right)\left(3x+2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=7\\x=\frac{-2}{3}\end{cases}}\)
2, \(x^3+3x^2-\left(x+3\right)=0\)
\(\Rightarrow x^2\left(x+3\right)-\left(x+3\right)=0\)
\(\Rightarrow\left(x+3\right)\left(x^2-1\right)=0\)
\(\Rightarrow\left(x+3\right)\left(x-1\right)\left(x+1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=-3\\x=\pm1\end{cases}}\)
3, \(15x-5+6x^2-2x=0\)
\(\Rightarrow\left(15x-5\right)+\left(6x^2-2x\right)=0\)
\(\Rightarrow5\left(3x-1\right)+2x\left(3x-1\right)=0\)
\(\Rightarrow\left(3x-1\right)\left(5+2x\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x-1=0\\5+2x=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{3}\\x=\frac{-5}{2}\end{cases}}\)
4, \(5x-2-25x^2+10x=0\)
\(\Rightarrow\left(5x-25x^2\right)-\left(2-10x\right)=0\)
\(\Rightarrow5x\left(1-5x\right)-2\left(1-5x\right)=0\)
\(\Rightarrow\left(1-5x\right)\left(5x-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}1-5x=0\\5x-2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{1}{5}\\x=\frac{2}{5}\end{cases}}\)
1,a) 695- [200+ (11- 12)]
= 695- [200+ (11- 1)]
= 695- [200+ 10]
= 695- 210
= 485
b) (519: 517+ 3): 7
= (52+ 3): 7
= (25+ 3): 7
= 28: 7
= 4
c) 129- 5[29- (6- 12)]
= 129- 5[29- (6- 1)]
= 129- 5[29- 5]
= 129- 5. 24
= 129- 120
= 9
3,a) 2x- 49= 5. 32
2x- 49= 5. 9
2x- 49= 45
2x = 45+ 49
2x = 94
x = 94: 2
x = 47
c) 2x- 15= 17
2x = 17+ 15
2x = 32
2x = 25
=> x = 5
Câu 3b bạn tự làm nhé, xin loiosxn vì không giúp được cả bài.
CHÚC BẠN HỌC GIỎI !!!
MÌNH TÌM RA CÁCH LÀM CÂU 3b RỒI !!!
5x+ 2x= 45+ 20: 15
5x+ 2x= 45+ \(\frac{4}{3}\)
5x+ 2x= \(\frac{139}{3}\)
(5+ 2)x=\(\frac{139}{3}\)
7x =\(\frac{139}{3}\)
x =\(\frac{139}{3}\): 7
x =\(\frac{139}{21}\)
CHÚC BẠN HỌC GIỎI !!!
Nguyễn Khánh Phương
Bài 1 :
a) 149 - ( 35 : x + 3 ) x 17 = 13
( 35 : x + 3 ) x 17 = 149 - 13
( 35 : x + 3 ) x 17 = 136
( 35 : x + 3 ) = 136 : 17
( 35 : x + 3 ) = 8
35 - x = 8 - 3
35 - x = 5
x = 35 - 5
x = 30
b, 121 : 11 − ( 4x + 5 ) : 3 = 4
11 − 4x + 5 : 3 = 4
4x + 5 : 3 = 11 − 4
4x + 5 : 3 = 7
4x + 5 = 7 x 3
4x + 5 = 21
4x = 21 − 5
4x = 16
x = 16 : 4
x = 4
a, \(5x\left(x-1\right)+\left(x+17\right)=0\)
\(\Leftrightarrow5x^2-5x+x+17=0\Leftrightarrow5x^2-4x+17=0\)
\(\Leftrightarrow5\left(x^2-\frac{4}{5}x\right)+17=0\Leftrightarrow5\left(x^2-2.\frac{2}{5}x+\frac{4}{25}-\frac{4}{25}\right)+17=0\)
\(\Leftrightarrow5\left(x-\frac{2}{5}\right)^2-\frac{4}{5}+17=0\Leftrightarrow5\left(x-\frac{2}{5}\right)^2+81\ge81>0\)
Vậy pt vô nghiệm
b, \(3x\left(x-3\right)^2-3x\left(x+3\right)^2=0\)
\(\Leftrightarrow3x\left[\left(x-3\right)^2-\left(x+3\right)^2\right]=0\)
\(\Leftrightarrow3x\left(x-3-x-3\right)\left(x-3+x+3\right)=0\Leftrightarrow x.2x=0\Leftrightarrow x=0\)
c, \(2x^2-9x+7=0\Leftrightarrow2x^2-7x-2x+7=0\)
\(\Leftrightarrow x\left(2x-7\right)-\left(2x-7\right)=0\Leftrightarrow\left(x-1\right)\left(2x-7\right)=0\Leftrightarrow x=1;x=\frac{7}{2}\)
Trả lời:
a, \(5x\left(x-1\right)+\left(x+17\right)=0\)
\(\Leftrightarrow5x^2-5x+x+17=0\)
\(\Leftrightarrow5x^2-4x+17=0\)
\(\Leftrightarrow5\left(x^2-\frac{4}{5}x+\frac{17}{5}\right)=0\)
\(\Leftrightarrow x^2-\frac{4}{5}x+\frac{17}{5}=0\)
\(\Leftrightarrow x^2-2.x.\frac{2}{5}+\frac{4}{25}+\frac{81}{25}=0\)
\(\Leftrightarrow\left(x-\frac{2}{5}\right)^2+\frac{81}{25}=0\)
Vì \(\left(x-\frac{2}{5}\right)^2+\frac{81}{25}\ge\frac{81}{25}>0\forall x\)
nên pt vô nghiệm
b, \(3x\left(x-3\right)^2-3x\left(x+3\right)^2=0\)
\(\Leftrightarrow3x\left[\left(x-3\right)^2-\left(x+3\right)^2\right]=0\)
\(\Leftrightarrow3x\left(x-3-x-3\right)\left(x-3+x+3\right)=0\)
\(\Leftrightarrow3x.\left(-9\right).2x=0\)
\(\Leftrightarrow-54x^2=0\)
\(\Leftrightarrow x^2=0\)
\(\Leftrightarrow x=0\)
Vậy x = 0 là nghiệm của pt.
c, \(7-9x+2x^2=0\)
\(\Leftrightarrow2x^2-7x-2x+7=0\)
\(\Leftrightarrow x\left(2x-7\right)-\left(2x-7\right)=0\)
\(\Leftrightarrow\left(2x-7\right)\left(x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}2x-7=0\\x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{7}{2}\\x=1\end{cases}}}\)
Vậy x = 7/2; x = 1 là nghiệm của pt.
d, trùng ý c
a, \(x^3+3x^2-\left(x+3\right)=0\Leftrightarrow x^2\left(x+3\right)-\left(x+3\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x+1\right)\left(x+3\right)=0\Leftrightarrow x=1;x=-1;x=-3\)
b, \(15x-5+6x^2-2x=0\Leftrightarrow5\left(3x-1\right)+2x\left(3x-1\right)=0\)
\(\Leftrightarrow\left(2x+5\right)\left(3x-1\right)=0\Leftrightarrow x=-\frac{5}{2};x=\frac{1}{3}\)
c, \(5x-2-25x^2+10x=0\)
\(\Leftrightarrow\left(5x-2\right)-5x\left(5x-2\right)=0\Leftrightarrow\left(1-5x\right)\left(5x-2\right)=0\Leftrightarrow x=\frac{2}{5};x=\frac{1}{5}\)
Tính nhanh :
= -167 x 83 + (-167) x 17 - 33
= (-167) x (83+17) - 33
= (-167) x 100 - 33
= -16700-33 = -16733
Tìm x :
a, => 49-x^2=0 ( vì x^2+1 > 0 )
=> x^2=49
=> x=7 hoặc x=-7
b, => 3-x=0 hoặc 8-x=0
=> x=3 hoặc x=8
c, => x+2=0 hoặc x-3=0
=> x=-2 hoặc x=3
Tk mk nha
t làm Ngếu Ngáo câu A. đúng thì đúng mà sai thi thôi nhé
(-100-67) x (80+3)+(100+67) x(-10-7)-33 ( phá ngoặc)
\(-100-67\times80+3+100+67\times\left(-10\right)-7-33\) ( rút gọn)
\(\left(80+3-40\right)\times\left(-10\right)\) ( tính )
\(43\times\left(-10\right)=-430\)
ko biêt đúng hay sai đâu kk