Tìm x, biết
8x - |4x+3/4| =x+2
tìm x biết
a)4x^2+4x-3=0
b)x^4-3x^3-x+3=0
c)x^2(x-1)-4x^2+8x-4=0
\(4x^2+4x-3=0\)
\(\left[\left(2x\right)^2+2.2x.1+1\right]-4=0\)
\(\left(2x+1\right)^2-2^2=0\)
\(\left(2x+1-2\right).\left(2x+1+2\right)=0\)
\(\left(2x-1\right).\left(2x+3\right)=0\)
\(\Rightarrow\orbr{\begin{cases}2x-1=0\\2x+3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=-\frac{3}{2}\end{cases}}}\)
Vậy \(\orbr{\begin{cases}x=\frac{1}{2}\\x=-\frac{3}{2}\end{cases}}\)
\(x^4-3x^3-x+3=0\)
\(x^3.\left(x-3\right)-\left(x-3\right)=0\)
\(\left(x-3\right).\left(x^3-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-3=0\\x^3-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=3\\x=1\end{cases}}}\)
Vậy \(\orbr{\begin{cases}x=3\\x=1\end{cases}}\)
\(x^2.\left(x-1\right)-4x^2+8x-4=0\)
\(x^2.\left(x-1\right)-\left[\left(2x\right)^2-2.2x.2+2^2\right]=0\)
\(x^2.\left(x-1\right)-\left(2x-2\right)^2=0\)
\(x^2.\left(x-1\right)-4.\left(x-1\right)^2=0\)
\(\left(x-1\right).\left[x^2-4.\left(x-1\right)\right]=0\)
\(\left(x-1\right).\left[x^2-2.x.2+2^2\right]=0\)
\(\left(x-1\right).\left(x-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-1=0\\x-2=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\x=2\end{cases}}}\)
Vậy \(\begin{cases}x=1\\x=2\end{cases}\)
Tham khảo nhé~
tìm x biết
a)4x^2+4x-3=0
b)x^4-3x^3-x+3=0
c)x^2(x-1)-4x^2+8x-4=0
tìm x biết rằng a)8x^4/2x^3+3x^3/x^2=15 b)16x^3/8x^2+4x^2/2x
Tìm x biết
8x - |4x+3/4|=x+2
<=> 7x - 2 = |4x + 3/4| (1)
Nếu x < 2/7 thì VT(1) < 0 còn VP(1) >=0 với mọi x nên PT vô nghiệm.Nếu x >= 2/7 thì 4x + 3/4 >0 do đó: |4x + 3/4| = 4x + 3/4(1) <=> 7x - 2 = 4x + 3/4 <=> 3x = 11/4 <=> x = 11/12 (TM >2/7)
Vậy, PT có nghiệm x = 11/12.
Tìm x, biết:
a) ( x 2 - 4x + 16)(x + 4) - x(x + l)(x + 2) + 3 x 2 = 0;
b) (8x + 2)(1 - 3x) + (6x - l)(4x -10) = -50.
a) Thực hiện rút gọn VT = -2x – 64
Giải phương trình -2x – 64 = 0 thu được x = -32.
b) Thực hiện rút gọn VT = -62 x +12
Giải phương trình -62x + 12 = -50 thu được x = 1.
Tìm x, biết: x3-x2=4x2-8x+4
x3-x2=4x2-8x+4
<=>x2(x-1)=4(x2-2x+1)
<=>x2(x-1)=4(x-1)2
<=>x2(x-1)-4(x-1)2=0
<=>(x-1)(x2-4x+4)=0
<=> (x-1)(x-2)2=0
<=>x-1=0 hoặc x-2=0
<=>x=1 hoặc x=2
x3 - x2 = 4x2 - 8x + 4
x3 - x2 - 4x2 + 8x - 4 = 0
x2(x - 1) - 4(x - 1)2 = 0
(x - 1)(x - 2)(x + 2) = 0
=> x - 1 = 0 hoặc x - 2 = 0 hoặc x + 2 = 0
=> x = 1 hoặc x = + 2
Tìm x, biết: x3-x2=4x2-8x+4
\(x^3-x^2=4x^2-8x+4\)
\(\Leftrightarrow x^2\left(x-1\right)=4\left(x^2-2x+1\right)\)
\(\Leftrightarrow x^2\left(x-1\right)-4\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^2-4\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x-1=0\\x-2=0\\x+2=0\end{array}\right.\) \(\Leftrightarrow\left[\begin{array}{nghiempt}x=1\\x=2\\x=-2\end{array}\right.\)
x3-x2=4x2-8x+4
<=>x2(x-1)=4(x2-2x+1)
<=>x2(x-1)=4(x-1)2
<=>x2(x-1)-4(x-1)2=0
<=>(x-1)(x2-4x+4)=0
<=> (x-1)(x-2)2=0
<=>x-1=0 hoặc x-2=0
<=>x=1 hoặc x=2
Tìm x biết : (8x-3)(3x+2)-(4x+7)(x+4)=(2x+1)(5x-1)
\(\left(8x-3\right)\left(3x+2\right)-\left(4x+7\right)\left(x+4\right)=\left(2x+1\right)\left(5x-1\right)\)
\(\Leftrightarrow24x^2+7x-6-\left(4x^2+23x+28\right)=10x^2+3x-1\)
\(\Leftrightarrow20x^2-16x-34=10x^2+3x-1\)
\(\Leftrightarrow10x^2-19x-33=0\)
\(\Leftrightarrow10x^2-30x+11x-33=0\)
\(\Leftrightarrow10x\left(x-3\right)+11\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(10x+11\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\10x+11=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-\frac{11}{10}\end{cases}}\)
Vậy \(x\in\left\{3;-\frac{11}{10}\right\}.\)
Bài làm :
Ta có :
\(\left(8x-3\right)\left(3x+2\right)-\left(4x+7\right)\left(x+4\right)=\left(2x+1\right)\left(5x-1\right)\)
\(\Leftrightarrow24x^2+7x-6-\left(4x^2+23x+28\right)=10x^2+3x-1\)
\(\Leftrightarrow20x^2-16x-34=10x^2+3x-1\)
\(\Leftrightarrow10x^2-19x-33=0\)
\(\Leftrightarrow10x^2-30x+11x-33=0\)
\(\Leftrightarrow10x\left(x-3\right)+11\left(x-3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(10x+11\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\10x+11=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=3\\x=-\frac{11}{10}\end{cases}}\)
Vậy x=3 hoặc x=-11/10
tìm x:
a.(x-3)^4-(x+3)^4+24x^3=216
b.(2x+1)(16x^4-8x^3+4x^2-2x+1)-(2x-1)(16x^4+8x^3+4x^2+2x+1)=2
tìm GTNN của bt:
x^2+2x+4
x^2-x-5/3/4
4x^2-x-3/16