tìm số thực x bt
(3x-5/12)^2-121/64=0
Tìm số thực x biết
(3x-5/12)^2-121/64=0
\(\left(3x-\frac{5}{12}\right)^2-\frac{121}{64}=0\)
\(\left(3x-\frac{5}{12}\right)^2=\frac{121}{64}\)
\(3x-\frac{5}{12}=\sqrt{\frac{121}{64}}\)
\(3x-\frac{5}{12}=\frac{11}{8}\)
\(3x=\frac{11}{8}+\frac{5}{12}\)
\(3x=\frac{33}{24}+\frac{10}{24}\)
\(3x=\frac{43}{24}\)
\(x=\frac{43}{24}:3\)
\(x=\frac{43}{24}\cdot\frac{1}{3}\)
\(x=\frac{43}{72}\)
Tim so thuc X,biet:
(3x-5/12)^2-121/64=0
Tìm x:
\(\left(3x-\dfrac{5}{12}\right)^2-\dfrac{121}{64}=0\)
\(\left(3x-\dfrac{5}{12}\right)^2-\dfrac{121}{64}=0\)
\(\left(3x-\dfrac{5}{12}\right)^2\) \(=0+\dfrac{121}{64}\)
\(3x-\dfrac{5}{12}\) \(=\sqrt{\dfrac{121}{64}}=\dfrac{11}{8}\)
\(3x\) \(=\dfrac{11}{8}+\dfrac{5}{12}=\dfrac{33+10}{24}=\dfrac{43}{24}\)
\(x\) \(\dfrac{3.43}{24}=\dfrac{43}{8}\)
Tìm số tự nhiên x biết:
a) x – 32 : 16 = 48
b) 88 – 3.(7+x) = 64
c) (5+4x) : 3 – 121 : 11 = 4
d) 15 – 2(3x+1) = 11.13 – 130
a) x – 32 : 16 = 48 ó x – 2 = 48 ó x = 48 + 2 ó x = 50
b) 88 – 3.(7+x) = 64 ó 3.(7+x) = 88 – 64 ó 7 + x = 24:3 ó x = 8 – 7 ó x = 1
c) (5+4x) : 3 – 121 : 11 = 4 ó (5+4x) : 3 – 11 = 4 ó (5+4x) : 3 = 4 + 11 ó 5+4x = 15.3 ó 4x = 45 – 5 ó 4x = 40 ó x = 10
d) 15 – 2(3x+1) = 11.13 – 130 ó 15 – 2(3x+1) = 143 – 130 ó 15 – 2(3x+1) = 13
ó 2(3x+1) = 15 – 13 ó 3x + 1 = 2:2 ó 3x = 1 – 1 ó 3x = 0 ó x = 0
Bài 4. Tìm số nguyên x, biết:
a) (x2 −9)(5x+15) =0 |
|
| b) x2 – 8x= 0 |
c) 5+12.(x−1)2 = 53 |
|
| d) (x− 5)2 = 36 |
e) (3x+−5)3 = 64 |
|
| f) 42x + 24x+3 = 144 |
Lời giải:
a. $(x^2-9)(5x+15)=0$
$\Rightarrow x^2-9=0$ hoặc $5x+15=0$
Nếu $x^2-9=0$
$\Rightarrow x^2=9=3^2=(-3)^2$
$\Rightarrow x=3$ hoặc $-3$
Nếu $5x+15=0$
$\Rightarrow x=-3$
b.
$x^2-8x=0$
$\Rightarrow x(x-8)=0$
$\Rightarrow x=0$ hoặc $x-8=0$
$\Rightarrow x=0$ hoặc $x=8$
c.
$5+12(x-1)^2=53$
$12(x-1)^2=53-5=48$
$(x-1)^2=48:12=4=2^2=(-2)^2$
$\Rightarrow x-1=2$ hoặc $x-2=-2$
$\Rightarrow x=3$ hoặc $x=0$
d.
$(x-5)^2=36=6^2=(-6)^2$
$\Rightarrow x-5=6$ hoặc $x-5=-6$
$\Rightarrow x=11$ hoặc $x=-1$
e.
$(3x-5)^3=64=4^3$
$\Rightarrow 3x-5=4$
$\Rightarrow 3x=9$
$\Rightarrow x=3$
f.
$4^{2x}+2^{4x+3}=144$
$2^{4x}+2^{4x}.8=144$
$2^{4x}(1+8)=144$
$2^{4x}.9=144$
$2^{4x}=144:9=16=2^4$
$\Rightarrow 4x=4\Rightarrow x=1$
a,( x- 1)^5=1
b,(3x-1)^2=121
c,4^2x+1=64
d,(x-2)^5=32
e,7^x.7^2=2744.73
Tìm x thuộc N
(x-1)5=1
(x-1)5=15
x-1=1
x=1+1
x=2
(3x-1)2=121
(3x-1)2=112
3x-1=11
3x=11+1
3x=12
x=12:3
x=4
42x+1=64
42x+1=43
=>2x+1=3
=>2x=3-1
=>2x=2
=>x=2:2
=>x=1
(x-2)5=32
(x-2)5=25
x-2=2
x=2+2
x=4
Tìm x bt
a) (x-5) + (x-7) = -12
b) 3x - 44 = -109 -2x
c) 2 ( x-5) - 5 (3+x) =-109
d) (x-3) . (x+5 ) < 0
\(a.\)
\(\Leftrightarrow x-5+x-7=-12.\)
\(\Leftrightarrow x=-12+-12\)
\(\Leftrightarrow x=-24\)
\(b.\)
\(\Leftrightarrow3x+2x=-109+44\)
\(\Leftrightarrow5x=-65\)
\(\Rightarrow x=-13\)
\(c.\)
\(\Leftrightarrow2x-10-15+5x=-109\)
\(\Leftrightarrow2x-5x=-109+15+10\)
\(\Leftrightarrow3x=-84\)
\(\Rightarrow x=-28\)
\(d.\)
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d) \(\left(x-3\right)\left(x+5\right)< 0\)
\(\Leftrightarrow\orbr{\begin{cases}x-3< 0\\x+5< 0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x< 3\\x< -5\end{cases}}\)
ko xem dc de ban oi :/
4) tìm số tự nhiên bt rằng
a) 4^11*25^11< 2^n*5^n < 20^12 * 5^12
b)4^5+4^5+4^5+4^5/3^5+3^5+3^5* 6^5+6^5+6^5+6^5+6^5+6^5/2^5+2^2=2n
5) Tìm x bt: x*(6-x)2003=(6-x)2003
6) Tìm x và y bt: (3x-5)^100+(2y+1)^200< 0
7)Tìm hai số tự nhiên m,n bt: 2m+2n=2m+n
8) Tìm các số nguyên x và y sao chp: (x+2)2+2(y-3)2<3
nhanh cái nào hehe