A, (x-2)^2=4x^2+4x+1 B, 25x^2-9=0 C, (2x-1)^2+(x+3)^2-5(x+7)(x-7)=0 D, (2x+1)(x-4)-2(x-3)^2=8 E, (3x-1)^2=(5-x)^2
bài 3 tìm x
a)(2x+3)^2-(2x+1)(2x-1)=32
b)(4x+3)(4x-3)-(4x-5)^2=46
c)(x+4)^2+(x+3)(x-3)-5(x+1)(x-1)=16
d)92x-1)^2+(x+3^2-5(x+7)(x-7)=0
e)25x^2-9=0
Bài 1: rút gọn
a. ( x + 1)^2 - (x - 1)^2 - 3(x + 1)(x - 1)
b. 5(x +2)(x -2) - 1/2(6 - 8x)^2 + 17
c. (x^2 - 1)^3 - (x^4 + x^2 + 1)(x^2 - 1)
d. (x^4 - 4x^2 +9)(x^2 + 3) - (3 + x^2)^3
e. (x-3)^3 -(x - 3)(x^2 +3x + 9) + 6(x + 1)^2
Bài 2: tìm x
a. 25x^2 - 9 = 0
b. (x + 4)^2 - (x + 1) (x -1) = 16
c. (2x - 1)^2 + (x + 3)^2 - 5(x + 7)(x - 7) = 0
d. (x + 2)(x^2 - 2x + 4) - x(x^2 + 2)= 15
e. (x + 3)^3 - x(3x + 1)^2 + (2x + 1)(4x^2 - 2x + 1) = 28
g. (x^2 - 1)^3 - (x^4 + x^2 + 1)(x^2 -1) = 0
HELP ME!!!!!!!!
Bn gửi từng câu sẽ có nhều ng trl hơn nhé
tý mk giải câu a cho cần ko
a) 9-64x^2=0
=> 64x^2 = 8
=> \(x^2=\frac{8}{64}=\frac{1}{8}\)
=> \(x=\frac{1}{\sqrt{8}}\)
b ) 25x^2 - 3 = 0
=> 25x^2 = 3
=> \(x^2=\frac{3}{25}\)
=> \(x=\frac{\sqrt{3}}{5}\)
C) 7 - 16x^2 =0
=> 16x^2 = 7
=> \(x^2=\frac{7}{16}\)
=> \(x=\frac{\sqrt{7}}{4}\)
d) 4x^2 - (x-4)^2 = 0
=> 4x^2 - x^2 + 8x - 16 =0
=> 3x^2 + 8x -16 = 0
=> ( 3x^2 + 12x ) - ( 4x +16 ) = 0
=> 3x( x + 4 ) - 4( x + 4 ) = 0
=>( x + 4 )( 3x - 4 ) = 0
=> \(\orbr{\begin{cases}x+4=0\\3x-4=0\end{cases}}\)
=> \(\orbr{\begin{cases}x=-4\\x=\frac{4}{3}\end{cases}}\)
e) ( 3x + 4 )^2 - ( 2x - 5 )^2 = 0
=> ( 3x + 4 + 2x - 5 )( 3x + 4 - 2x + 5 ) = 0
=> ( 5x -1 ) ( x + 9 ) = 0
=> \(\orbr{\begin{cases}5x-1=0\\x+9=0\end{cases}}\)
=> \(\orbr{\begin{cases}x=\frac{1}{5}\\x=-9\end{cases}}\)
Trả lời:
a, \(9-64x^2=0\)
\(\Leftrightarrow\left(3-8x\right)\left(3+8x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}3-8x=0\\3+8x=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{8}\\x=-\frac{3}{8}\end{cases}}}\)
Vậy x = 3/8; x = - 3/8 là nghiệm của pt.
b, \(25x^2-3=0\)
\(\Leftrightarrow\left(5x-\sqrt{3}\right)\left(5x+\sqrt{3}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}5x-\sqrt{3}=0\\5x+\sqrt{3}=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{\sqrt{3}}{5}\\x=-\frac{\sqrt{3}}{5}\end{cases}}}\)
Vậy \(x=\pm\frac{\sqrt{3}}{5}\)
c, \(7-16x^2=0\)
\(\Leftrightarrow\left(\sqrt{7}-4x\right)\left(\sqrt{7}+4x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}\sqrt{7}-4x=0\\\sqrt{7}+4x=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{\sqrt{7}}{4}\\x=-\frac{\sqrt{7}}{4}\end{cases}}}\)
Vậy \(x=\pm\frac{\sqrt{7}}{4}\)
d, \(4x^2-\left(x-4\right)^2=0\)
\(\Leftrightarrow\left(2x-x+4\right)\left(2x+x-4\right)=0\)
\(\Leftrightarrow\left(x+4\right)\left(3x-4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+4=0\\3x-4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-4\\x=\frac{4}{3}\end{cases}}}\)
Vậy x = - 4; x = 4/3 là nghiệm của pt.
e, \(\left(3x+4\right)^2-\left(2x-5\right)^2=0\)
\(\Leftrightarrow\left(3x+4-2x+5\right)\left(3x+4+2x-5\right)=0\)
\(\Leftrightarrow\left(x+9\right)\left(5x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+9=0\\5x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-9\\x=\frac{1}{5}\end{cases}}}\)
Vậy x = - 9; x = 1/5 là nghiệm của pt.
Tìm x, biết :
a, ( x-3)^3 - ( x-3) ( x^2 + 3x+9) + 9( x+1)^2 = 15
b, 4x^2 - 81 = 0
c, x(x-5) ( x+5) - ( x-2) ( x^2 + 2x + 4 ) = 3
d, 25x^2 - 2 = 0
e, ( x+2)^2 = ( 2x-1)^2
f, ( x+2)^2 - x+4 = 0
- Tại câu a có hai bạn ra hai đáp án nên góp thêm lựa ý kiến cho người hỏi đỡ bối rối
a, Ta có : \(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+9\left(x+1\right)^2=15\)
=> \(\left(x-3\right)\left(x^2-6x+9-x^2-3x-9\right)+9\left(x+1\right)^2=15\)
=> \(9\left(x+1\right)^2-9\left(x^2-3x\right)=15\)
=> \(9\left(x^2+2x+1-x^2+3x\right)=15\)
=> \(9\left(5x+1\right)=15\)
=> \(5x=\frac{15}{9}-1=\frac{2}{3}\)
=> \(x=\frac{2}{15}\)
Vậy ....
1. Tìm x:
a, 25x2-9=0
b, (x+4)2-(x+9).(x-1)=16
c, x2-2x-(x-5)=0
d, (2x-1)2+(x+3)2+5.(x+7).(x-7)=0
e, (2x-1)2-(4x2-1)=0
a/ \(25x^2-9=0\)
<=> \(\left(5x-3\right)\left(5x+3\right)=0\)
<=> \(\orbr{\begin{cases}5x-3=0\\5x+3=0\end{cases}}\)
<=> \(\orbr{\begin{cases}5x=3\\5x=-3\end{cases}}\)
<=> \(\orbr{\begin{cases}x=\frac{3}{5}\\x=-\frac{3}{5}\end{cases}}\)
b/ \(\left(x+4\right)^2-\left(x+9\right)\left(x-1\right)=16\)
<=> \(x^2+8x+16-x^2+8x-9=16\)
<=> \(16x+7=16\)
<=> \(16x=9\)
<=> \(x=\frac{9}{16}\)
a) \(25x^2-9=0\)
\(\Leftrightarrow\left(5x-3\right)\left(5x+3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}5x-3=0\\5x+3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}5x=3\\5x=-3\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{3}{5}\\x=-\frac{3}{5}\end{cases}}}\)
Vậy S = {3/5 ; -3/5}
b) \(\left(x+4\right)^2-\left(x+9\right)\left(x-1\right)=16\)
\(\Leftrightarrow\left(x+4\right)^2-4^2-\left(x+9\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left(x+4-4\right)\left(x+4+4\right)-\left(x+9\right)\left(x-1\right)=0\)
\(\Leftrightarrow x\left(x+8\right)-\left(x+9\right)\left(x-1\right)=0\)
\(\Leftrightarrow x^2+8x-x^2-8x+9=0\)
\(\Leftrightarrow9=0\left(vl\right)\)
Vậy S = \(\varnothing\)
Bài 1:
a)-2x-3.( x-17 )= 34-2.( -x+25 )
b)17x+3.( -16x-37 )= 2x+43-4x
c){-3x+2. [ 45-x-3 ( 3x+7 ) -2x]+4x} = 55
g)-103-57: [ 5.( 2x-1 )2-( -9 )0 ]
Bài 2:
a)-5.( -x+7 )-3.( -x-5 )=-4.( 12-x )+48
b)7.( -x-7 )-4.( -2x-11 )=7.( 4x+10 )+9
c)-2.( 15-3x )-4.( -7x+8 )=-5-9.( -2x+1 )
d)5.( -3x-7 )-4.( -2x-11 )=7.( 4x+10 )+9
e)4( x-2 )2-13=( -3 )2.2-11.( -3 )
f)-52-( 2x-1 )3=( -13 ).( -3 )
1)4x-20=0 ; 2) 5x+15=0 ; 3) 3x-5=7x+2 ; 4) 4x-(x-1)=2(1+x) ; 5) x2 -2x=0 ; 6) 2(3x-5)-3(x-2)=3(x+4) ; 7) (x+3)(2x-7)=0
8) 5x(x-3)+2x-6=0 ; 9) (3x-1)(2x-1)-(3x-1)(x+2)=0
10)|2x-1|+1=8 ; 11) |x-2|=3x+1 ; 12) |2x|=21-x
Giải các phương trình nha mọi người ^_^
Tìm x
1. (3x+5)(4-3x)=0
2. 9(3x-2)=x(2-3x)
3. 25x^2 -2=0
4. x^2- 25=6x-9
5. (2x-1)^2-(2x+5)(2x-5)=18
6. x^3-8=(x-2)^3
7. x^3-4x^2+4x=0
8. x^2- 25+2(x+5)=0
9. 2(x^2+8x+16)- x^2+4=0
10. x^2(x-2)+7x=14
(3x+5)(4-3x)=0
3x+5 =0 hoặc 4-3x=0
3x=-5 hoặc 3x=-4
x=-5/3 hoặc x=-4/3
9(3x-2)=x(2-3x)
9(3x-2)-x(3x-2)=0
(3x-2)(9-x)=0
3x-2=0 hoặc 9-x=0
3x=2 hoặc x= -9
x =2/3 hoặc x=-9
vậy x =2/3 ; x= -9
25x^2 - 2=0
(5x)^2 -√2^2=0
(5x-√2)(5x+√2)=0
5x=√2 hoặc 5x = -√2
x=√2/5 hoặc x= -√2/5
vậy x=√2/5 ; x=-√2/5
Tìm x ( bài tập xoắn 3 đại số 8 )
1. 25x mũ 2 - 20x + 4 = 0
2. ( 2x - 3 ) mũ 2 - ( 2x + 1 ) ( 2x - 1 ) = 0
3. ( 1/2x - 1 ) ( 1/2x + 1 ) - ( 1/2x - 1 ) mũ 2 = 0
4. ( 2x - 3 ) mũ 2 + ( 2x + 5 ) mũ 2 = 8 ( x + 1 ) mũ 2
5. 4x mũ 2 + 12x -7 = 0
6. 1/4x mũ 2 + 2/3x - 5/9 = 0
7. 24 và 8/9 ( hỗn số ) - 1/4x mũ 2 - 1/3x = 0
bn kiểm tra giúp mk đề 2 câu cuối , mk làm ko ra