Tìm X biết
( X * 2 +2.7 ) /30 =0.32
Tìm x, biết:
a,x/-15=-60/x
b,-2/x=-x/0.32
a) \(-\frac{x}{15}=-\frac{60}{x}\Rightarrow-15.\left(-60\right)=x^2\Rightarrow900=x^2\Rightarrow x=\sqrt{900}=30\)
\(x=-\sqrt{900}=-30\)
b) \(-\frac{2}{x}=-\frac{x}{0,32}\Rightarrow-2.\left(-0,32\right)=x^2\Rightarrow\frac{16}{25}=x^2\Rightarrow x=\frac{\sqrt{16}}{\sqrt{25}}=\frac{4}{5}\)
\(x=-\frac{\sqrt{16}}{\sqrt{25}}=-\frac{4}{5}\)
a) \(\frac{x}{-15}=\frac{-60}{x}\)
=> x.x = (-60) . (-15)
=>x2 = 900
=>x2 = 302
=>x=30
b)\(\frac{-2}{x}=\frac{-x}{0,32}\)
=>x.(-x) =(-2).0,32
=>-(x2) =-0,64
=>-(x2) =-(0,82)
=>x=0,8
Bài 1: thực hiệ phép tính:
a) 555 : 5 + 225 : 15
b)95 - 5 . (30 - 2.7) + 10
c)65 : 63 + 5 . 32
d)-3 > x > 4
Bài 2 : Tìm x, biết:
a)6 . (x - 7) = 63
b)4 . (3x - 4) - 2 = 2 . 32
c)x ⋮ 12 và 100 < x < 150
Bài 3 : Tính diện tích hình thang cân ABCD biết đáy AB = 10 cm, đáy CD = 25cm, chiều cao AH = 7cm.
Ai bt bài này thù giúp mk nha .
Bài 2:
a: \(\Leftrightarrow x-7=36\)
hay x=43
Tìm x biết
219-7 ( x+1 ) = 10²
( 3x - 2⁴ ) . 7³ = 2.7⁴
219 - 7(x + 1) = 10²
7(x + 1) = 219 - 10²
7(x + 1) = 219 - 100
7(x + 1) = 119
x + 1 = 119 : 7
x + 1 = 17
x = 17 - 1
x = 16
--------------------
(3x - 2⁴) . 7³ = 2.7⁴
(3x - 16).7³ = 2.7⁴
3x - 16 = 2.7⁴:7³
3x - 16 = 2.7
3x - 16 = 14
3x = 14 + 16
3x = 30
x = 30 : 3
x = 10
Tìm x biết
219-7 ( x+1 ) = 10²
( 3x - 2⁴ ) . 7³ = 2.7⁴
Lời giải:
$10+2x=4^5:4^3=4^2=16$
$2x=16-10=6$
$x=6:2=3$
---------
$2x-6^2:18=3.2^2$
$2x-2=12$
$2x=14$
$x=14:2=7$
--------------
$70-5(x-3)=3.2^5=96$
$5(x-3)=70-3.2^5=-26$
$x-3=\frac{-26}{5}$
$x=3+\frac{-26}{5}=\frac{-11}{5}$
------------------
$19-7(x+1)=10^2=100$
$7(x+1)=19-100=-81$
$x+1=\frac{-81}{7}$
$x=\frac{-81}{7}-1=\frac{-88}{7}$
------------
$(3x-2^4).7^3=2.7^4$
$3x-16=2.7^4:7^3=2.7=14$
$3x=14+16=30$
$x=30:3=10$
Tìm x , biết :
a) 14-5+x=30
b) 45-(3+x)=14
c)18+(-3+x)-(44-x)=55
d) (x-45).27=0
e) 25.(42-x)=23
g) 156-(x+61)=82
h) 70-5(x-3)=45
i) | x+2 | = -(-8)+|-7|
k) (x-2)2 = 30-2.7
\(a,14-5+x=30\)
\(\Rightarrow9+x=30\Rightarrow x=30-9\)
\(\Rightarrow x=21\)
\(b,45-\left(3+x\right)=14\)
\(\Rightarrow3+x=45-14\)
\(\Rightarrow3+x=31\Rightarrow x=31-3\)
\(\Rightarrow x=28\)
\(c,18+\left(-3+x\right)-\left(44-x\right)=55\)
\(\Rightarrow18-3+x-44+x=55\)
\(\Rightarrow2x-29=55\Rightarrow2x=55+29\)
\(\Rightarrow2x=84\Rightarrow x=84:2\)
\(\Rightarrow x=42\)
\(d,\left(x-45\right).27=0\)
\(\Rightarrow x-45=0\Rightarrow x=45\)
\(a,14-5+x=30\)
\(\Rightarrow9+x=30\)
\(\Rightarrow x=30-9=21\)
\(b,45-\left(3+x\right)=14\)
\(\Rightarrow3+x=45-14=31\)
\(\Rightarrow x=31-3=28\)
Tìm x biết \(7^{x+2}+2.7^{x-1}=345\)
7x+2+2.7x-1=345
=>7x-1(73+2)=345
=>7x-1=345:345=1
=>x-1=0
=>x=1
7^x-1 . 7^x+3 + 2. 7^x-1 = 345
7^x-1 .(7^x+3 + 2) =345
7^x-1. (7^x+3 + 2) = 7^x+3 -2
7^x-1 =(7^x+3 - 2) : (7^x+3 +2)
7^x-1 = 0
=> x-1 = 1
chắc chắn luôn
Tìm X là số tự nhiên
2.5 x 2.7 < X x 2 < 2.7 x4.5
2,5 x 2,7 < X x 2 < 2,7 x 4,5
6,75 < X x 2 < 12,15
=> x = 4 ; 5 , 6
2,3 x 2,7 < X x 2 < 2,7 x 4,5
6,75 < X x 2 < 12,15
=> x = 4 ; 5 ; 6
Tìm x biết:
a) 7x+2 + 2.7x-1= 345
b) 2x+2 - 2x= 96
a.
\(7^{x+2}+2\times7^{x-1}=345\)
\(7^x\times7^2+2\times7^x\div7=345\)
\(7^x\times\left(7^2+\frac{2}{7}\right)=345\)
\(7^x\times\frac{345}{7}=345\)
\(7^x=345\div\frac{345}{7}\)
\(7^x=345\times\frac{7}{345}\)
\(7^x=7\)
\(x=1\)
b.
\(2^{x+2}-2^x=96\)
\(2^x\times\left(2^2-1\right)=96\)
\(2^x\times3=96\)
\(2^x=\frac{96}{3}\)
\(2^x=32\)
\(2^x=2^5\)
\(x=5\)
\(a,7^{x+2}+2.7^{x-1}=345\Rightarrow7^x.49+\frac{2}{7}.7^x=345\Rightarrow7^x\left(49+\frac{2}{7}\right)=345\Rightarrow7^x.\frac{345}{7}=345\Rightarrow7^x=345:\frac{345}{7}=7^1\Rightarrow x=1\)
\(b,2^{x+2}-2^x=96\Rightarrow2^x.4-2^x=96\Rightarrow2^x\left(4-1\right)=96\Rightarrow2^x.3=96\Rightarrow2^x=96:3=32\Rightarrow2^x=2^5\Rightarrow x=5\)
Tìm x biết:
a) 7x+2 + 2.7x-1= 345
b) 2x+2 - 2x= 96
\(a,7^{x+2}+2.7^{x-1}=345=>7^{x-1+3}+2.7^{x-1}=345=>7^{x-1}.7^3+2.7^{x-1}=345\)
\(=>\left(7^3+2\right).7^{x-1}=345=>345.7^{x-1}=345=>7^{x-1}=1=7^0=>x-1=0=>x=1\)
\(b,2^{x+2}-2^x=96=>2^x.2^2-2^x=96=>2^x.\left(4-1\right)=96=>2^x.3=96=>2^x=32=2^5=>x=5\)