Tính: 84 ÷ (4 ÷ 2) = ?
A. 10
B. 11
C. 42
D. 24
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2:
a: =4+3/8+5+2/3
=9+3/8+2/3
=216/24+9/24+16/24
=216/24+25/24
=241/24
b; =2+3/8+1+1/4+3+6/7
=6+3/8+1/4+6/7
=6+5/8+6/7
=419/56
c: \(=2+\dfrac{3}{8}-1-\dfrac{1}{4}+5+\dfrac{1}{3}\)
=6+3/8-1/4+1/3
=6+1/8+1/3
=6+11/24
=155/24
d: \(=3+\dfrac{5}{6}+6\cdot\dfrac{13}{6}\)
=3+13+5/6
=16+5/6
=101/6
e: =3+1/2+4+5/7-5-5/14
=3+4-5+1/2+5/7-5/14
=2+7/14+10/14-5/14
=2+12/14
=2+6/7=20/7
f: =9/2+1/2:11/2
=9/2+1/11
=99/22+2/22=101/22
2:
a: =4+3/8+5+2/3
=9+3/8+2/3
=216/24+9/24+16/24
=216/24+25/24
=241/24
b; =2+3/8+1+1/4+3+6/7
=6+3/8+1/4+6/7
=6+5/8+6/7
=419/56
c: \(=2+\dfrac{3}{8}-1-\dfrac{1}{4}+5+\dfrac{1}{3}\)
=6+3/8-1/4+1/3
=6+1/8+1/3
=6+11/24
=155/24
d: \(=3+\dfrac{5}{6}+6\cdot\dfrac{13}{6}\)
=3+13+5/6
=16+5/6
=101/6
e: =3+1/2+4+5/7-5-5/14
=3+4-5+1/2+5/7-5/14
=2+7/14+10/14-5/14
=2+12/14
=2+6/7=20/7
f: =9/2+1/2:11/2
=9/2+1/11
=99/22+2/22=101/22
Lời giải:
$10+2.4^2=10+2.16=10+32=42$
Đáp án A
$50-4.3^2=50-4.9=50-36=14$
Đáp án A.
a)Ta có 60 = 2 2 .3. 5; 280 = 2 3 .5.7
BCNN(60; 280) = 2 3 . 3.5.7= 840
b) Ta có: 84 = 2 2 .3.7; 108 = 2 2 . 3 3
BCNN(84; 108) = 2 2 . 3 3 .7 = 756
c) Ta có: 13 =13; 15= 3.5
BCNN(13; 15) = 13.3.5= 195.
d) Ta có; 10 = 2.5; 12 = 2 2 .3; 15 = 3.5
BCNN(10;12; 15) = 2 2 .3.5 = 60
e) Ta có: 8 = 2 3 ; 9 = 3 2 ; 11 = 11
BCNN(8; 9; 11) = 2 3 . 3 2 .11= 792
f) Ta có: 24 = 3. 2 3 ; 40 = 2 3 .5; 168 = 2 3 .3.7
BCNN(24; 40; 168)= 2 3 .3. 5.7= 840
Giải
a) 24 + (15-x) = 16
<=> 15-x=16-24
<=> 15-x=(-8)
<=> x = 15-(-8) => x = 23
b) 11 - (24-x) =
<=> 24-x= 11 - (-27)
<=> 24 - x = 38
<=> x = 24 - 38 => x = -14
c) |x-16| = 42
<=> x-16=42 và x-16=-42
<=> x = 42 + 16 ; x =-42+16
<=> x = 58 ; x = -26
d) 10-2|x| = (-2) . (-3)
<=> 10 - (-2) . (-3) = 2|x|
<=> 10 - 6 = 2|x|
<=> 2|x| = 4
<=> |x| = 4 : 2 = 2
=> x = 2 hoặc x = (-2)
A/ 24+(15-x)=16
(15-x)= 16- 24
(15-x)= - 18
x = 5 - (-18)
x = 23
B/ 11-(24-x)=(-3)3
(24-x)=11- 27
(24-x)= -16
x = 24 -(- 16)
x= 40
C/
\(\left|x-16\right|=42\hept{\begin{cases}x-16=42\\x-16=-42\end{cases}}\hept{\begin{cases}x=42+16\\x=-42+16\end{cases}}\hept{\begin{cases}x=58\\x=-26\end{cases}}\)
D/ 10-2|x|=(-2)x(-3)
10-2|x|=6
2|x|=10-6
2|x|=4
x=4:2
x=2
Đáp án C