x * 8 +(90 +15 ) = 775
giúp mình nè : tính nhanh\(a,\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{775}+\frac{1}{1147}\)
\(b,74\frac{19}{35}.\frac{7}{90}+15\frac{16}{35}.\frac{7}{90}\)
CẢM ƠN CÁC BẠN!!!
Bài 1:Tính
a) (-105)-75
b) 145+(-245)
c) 87-113
d) (-310)+(-90)
e) (-825)+(775+825)
g) ( 163-413)-(183-637)
Bài 2:Tìm x,biết:
a) x+24=-15-4
b) x + 73=-127
c) /x -1/=/-10/+2
d) x +145=131-(-169)
e) x-96=443=(-15)
Giúp mk nk thank kiu!!!
Bài 2:
a: x+24=-15-4=-19
=>x=-19-24=-43
b: x+73=-127
=>x=-127-73=-200
c: |x-1|=|-10|+2=10+2=12
=>x-1=12 hoặc x-1=-12
=>x=13 hoặc x=-11
d: x+145=131-(-169)=131+169=300
=>x=155
e: x-96=443-(-15)=443+15=458
=>x=554
Tính nhanh:
a) 1234-(874-121)-(24+3121)
b) 1000-(138+171)+(263-491)
c) -329+(15-101)-25-440
d) -825+(775+825)
e) (163-413)-(187-637)
g) [195+(-116)]-[-195+(-100)]-[90+(-16)]
f) [153-(-126)]+[-126-(-153)]
tính bằng cách hợp lí nhất
a, ( 3 và 1/15 - 1/11 ) x 11
b, 1/7 x 1/91 x 1/247 x 1/775 x 1/1147
tính bằng cách hợp lí nhất
a, ( 3 và 1/15 - 1/11 ) x 11
b, 1/7 x 1/91 x 1/247 x 1/775 x 1/1147
(14023 x 9 + 38942 x 8 + 13991 x 7) x (15 x 6 - 90)
$(14023 xx 9 + 38942 xx 8 + 13991 xx 7) xx (15 x 6 - 90)\\=(14023 xx 9 + 38942 xx 8 + 13991 xx 7) xx(90-90)\\(14023 xx 9 + 38942 xx 8 + 13991 xx 7) xx0\\=0$
(14023 x 9 + 38942 x 8 + 13991 x 7) x (15 x 6 - 90)
= (14023 x 9 + 38942 x 8 + 13991 x 7) x (90 - 90)
=(14023 x 9 + 38942 x 8 + 13991 x 7) x 0 = 0
11/15-(7/9+x)x3/8=61/90+x/3
\(\frac{11}{15}-\left(\frac{7}{9}+x\right).\frac{3}{8}=\frac{61}{90}+\frac{x}{3}\)(. là dấu nhân)
\(\Leftrightarrow\frac{11}{15}-\frac{7}{24}-\frac{3x}{8}-\frac{61}{90}-\frac{x}{3}=0\)
\(\Leftrightarrow\frac{-17}{72}-\left(\frac{3x}{8}+\frac{x}{3}\right)=0\)
\(\Leftrightarrow\frac{17x}{24}=-\frac{17}{72}\)
\(\Leftrightarrow17x.72=-17.24\)
\(\Leftrightarrow x=-\frac{1}{3}\)
\(\frac{11}{15}-\left(\frac{7}{9}+x\right).\frac{3}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{11}{15}-\frac{7}{9}.\frac{3}{8}-\frac{3x}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{11}{15}-\frac{7}{24}-\frac{3x}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{53}{120}-\frac{3x}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{53}{120}-\frac{61}{90}=\frac{8x+9x}{24}\)
\(\Rightarrow-\frac{17}{72}=\frac{17x}{24}\)
\(\Rightarrow\frac{-17}{72}.24=17x\)
\(\Rightarrow-17.3=17x\Leftrightarrow x=-3\)
5^15+25^7+5^13 chia hết cho 775 giúp mk với T.T mk cần gấp
\(5^{15}+25^7+5^{13}=5^{15}+\left(5^2\right)^7+5^{13}\)
\(=5^{15}+5^{14}+5^{13}=5^{11}\left(5^4+5^3+5^2\right)\)
\(=5^{11}.\left(625+125+25\right)=5^{11}.775⋮775\)
tìm X
[ ( 90 - 15 x X ) - 8 ] x 5 + 10 = 60 x 0,5
[(90-15xX)-8]x5+10=30
_____________=30-10
___________=20:5
_________=4+8
15xX=90-12
X=78:15
X=5.2
[(90-15x X)-8] x 5 + 10 = 60 x 0,5
[(90-15xX)-8] x 5 + 10 = 30
[(90-15xX)-8] x 5 = 30 - 10 = 20
(90-15xX)-8 = 20 : 5 = 4
90 - 15xX = 4 + 8 = 12
15xX = 90-12
15xX = 78
X = 78 : 15
X = 5,2