168:Ý-42:Y=6
(168 * 168-168*58) : 42
0,9*95+1,8* 2+0,9
có thể tính nhanh
(168 * 168-168*58) : 42
=18480 : 42
=440
0,9*95+1,8* 2+0,9
=90
Bài 3. Tìm x biết:
1) |x| = 10 2) |x - 8| = 0 3) 7 + |x| = 12
4) |x + 1| = 3 5) 15 - x = 16 - (14 - 42) 6) 210 - (x - 12) = 168
1/ `|x|=10<=> x=\pm 10`
2/ `|x-8|=0<=>x-8=0<=>x=8`
3/ `7+|x|=12<=>|x|=5<=>x=\pm 5`
4/ `|x+1|=3`
$\Leftrightarrow\left[\begin{array}{1}x+1=3\\x+1=-3\end{array}\right.\\\Leftrightarrow\left[\begin{array}{1}x=3\\x=-4\end{array}\right.$
5/ `15-x=16-(14-42)`
`<=>15-x=16+28`
`<=>15-x=44`
`<=>x=-29`
6/ `210-(x-12)=168`
`<=>210-x+12=168`
`<=>222-x=168`
`<=>x=54`
1.
\(\left|x\right|=10\Leftrightarrow x=\pm10\)
2.
\(\left|x-8\right|=0\Leftrightarrow x-8=0\Leftrightarrow x=8\)
3.
\(7+\left|x\right|=12\Leftrightarrow\left|x\right|=5\Leftrightarrow x=\pm5\)
32+x=64,m+42+42=168 hay so sanh x va m
cam on cac ban nhieu minh se ket ban tung ban
x = 64 - 32 = 32
m = 168 - 42 = 126
Vì m = 126
x = 32
=> m > x
Tinh nhanh:
\(\frac{\text{72+36*2+24*3+18*4+12*6+168}}{\text{2+2+4+6+10+16+26+42+68}}\)
chứng minh rằng nếu (a,30)=1 thì a4+59 chia hết cho 60
Chứng minh rằng nếu (a,42)=1 thì a6 đồng dư 1(mod 168)
. Tính nhanh: a) (45×105-225)-(210+42×95) b) (47×105-235)-(168+42×96) Giúp với ạ. E đang cần gấp.
a) \(\left(45x105-225\right)-\left(210+42x95\right)\)
\(=45x\left(100+5\right)-225-210+42x\left(100-5\right)\)
\(=4500+45x5-225-210+4200-42x5\)
\(=4500+4200+45x5-42x5-225-210\)
\(=8700+5x\left(45-42\right)-435\)
\(=8700+15-435=8280\)
a: =45*105-225-210-42*95
=45*(105-5)-42(95+5)
=100*3
=300
b: =47(105-5)-42(96+4)
=47*100-42*100
=5*100
=500
b) \(\left(47x105-235\right)-\left(168+42x96\right)\)
\(=47x\left(100+5\right)-235-168-42x\left(100-4\right)\)
\(=4700+235-235-168-4200-168\)
\(=4700-4200+235-235-168-168\)
\(=500\)
tìm x,y :
a,3x+5y=42
b,6x^2+5y^2=74
c,x^2+168
cho mình hỏi (x + 168) x 42 = 7500 bằng bao nhiêu
(X+168)=7500:42
X+168=178(du30)
x=178-168
x=1
Tính nhanh A=1,25+2,75+4,25+........+17,75+19,25
B=5,8.(168-100)+(4,5+1,3).(15+26)+(7,3-1,5)
C=1/6+1/12+1/20+1/30+1/42+1/56
Làm đúng tui cho 1 like (có trình bày)
A=1,25+2,75+4,25+........+17,75+19,25
A có ( 19,25 - 1,25 ) : 1,5 + 1 = 13 số hạng.
A = ( 19,25 + 1,25 ) . 13 : 2
A = 133,25
B = 5,8 . ( 168 - 100 ) + ( 4,5 + 1,3) . ( 15 + 26) + (7,3 - 1,5 )
B = 5,8 . 68 + 5,8 + 5,8
B = 5,8 ( 68 + 1 + 1 )
B = 5,8 . 70
B = 406
\(C=\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}\)
\(C=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}\)
\(C=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}\)
\(C=\frac{1}{2}-\frac{1}{8}\)
\(C=\frac{3}{8}\)