(1+2+3+...+9)x+25=205
(1+2+3+...+9)x x+25 =205
1 . \(\frac{x-1}{12}-\frac{2x-12}{14}=\frac{3x-14}{25}-\frac{3x-12}{27}\)
2 . \(\frac{2x-1}{2}+\frac{2x+1}{3}=\frac{2x+7}{6}+\frac{2x+9}{7}\)
3 . \(\frac{x^2+x+4}{2}+\frac{x^2+x+7}{3}=\frac{x^2+x+13}{5}+\frac{x^2+x+16}{6}\)
4 . \(\frac{201-x}{99}+\frac{203-x}{97}+\frac{205-x}{95}+3=0\)
Thực hiện các phép tính sau:
a) 107-{38+[7.3^2-24:6+(9-7)^3]}:15
b) 307-[(180-160):2^2+9]:2
c)205-[1200-(4^2-2.3)^3]:40
d)177:[2.(4^2-9)+3^2(15-10)]
e)[(25-2^2.3)+(3^2.4+16)]:5
Cau a la ban hay tinh trong dau ngoac don truoc sau do lam nhoac vuong va lam dau ngoac nhon va tinh cac phep tinh con lai
e)
=[(25-4.3)+(9.4+16)}:5
=[(25-12)+(36+1)]:5
=[13+52]:5
=65:5
=13
d)
=177:[2.(16-9)+9.5]
=177:[2.7+45]
=177:[14+45]
=177:59
=3
c)
=205-[1200-(16-6)3]:40
=205-[1200-103]:40
=205-[1200-1000]:40
=205-200:40
=205-5
=200
b)
=307-[20:4+9]:2
=307-[5+9]:2
=307-14:2
=307-7
=300
a)
=107-{38+[7.9-4+23]}:15
=107-{38+[63-4+8]}:15
=107-{38+[59+8]}:15
=107-{38+67]}:15
=107-105:15
=107-7
=100
a)40 * x=1440
b)x:13=205
c)2057
d)tính bằng cách thuạn tiện nhất:
36 x 25 x 4=?
18x24:9=?
41 x 2 x 8 x 5=?
215 x 86 + 215 x 14=?
53 x 128 - 43 x 128=?
2/3 x 4/7=?
2 x 3 x 4 / 2 x 3 x 4 x 5=?
1 x 2 x 3 x 4 / 5 x 6 x 7 x 8
x : 7/11=22
2/7 * x=2/3
a)1440:40 =36
b)205 x 13 =2665
c)2057
d)36 x 25 x 4 =3600
18 x 24 :9 =48
41 x 2 x 8 x 5 =3280
215 x 86 + 215 x 14 =21500
53 x 128 - 43 x 128 =1408
2/3 x 4/7 =8/21
2 x 3 x 4 / 2 x 3 x 4 x 5 =24/120
1 x 2 x 3 x 4 / 5 x 6 x 7 x 8=24/1680
x : 7/11 = 22
x =22 x 7/11
x =14
2/7 * x =2/3
x = 2/7 :2/3
x = 20/21
\(\frac{x-23}{24}+\frac{x-23}{25}=\frac{x-23}{26}\)
\(\Leftrightarrow\frac{x-23}{24}+\frac{x-23}{25}-\frac{x-23}{26}=0\)
\(\Leftrightarrow\left(x-23\right)\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}\right)=0\)
\(\Leftrightarrow x-23=0\left(vì\frac{1}{24}+\frac{1}{25}-\frac{1}{26}\ne0\right)\)
\(\Leftrightarrow x=23\)
vậy................
\(\frac{201-x}{99}+\frac{203-x}{97}+\frac{205-x}{95}+3=0\)
\(\Leftrightarrow\left(\frac{201-x}{99}+1\right)+\left(\frac{203-x}{97}+1\right)+\left(\frac{205-x}{95}+1\right)=0\)
\(\Leftrightarrow\frac{300-x}{99}+\frac{300-x}{97}+\frac{300-x}{95}=0\)
\(\Leftrightarrow\left(300-x\right)\left(\frac{1}{99}+\frac{1}{97}+\frac{1}{95}\right)=0\)
\(\Leftrightarrow300-x=0\left(vì\frac{1}{99}+\frac{1}{97}+\frac{1}{95}>0\right)\)
\(\Leftrightarrow x=300\)
vậy..........
Ta có: 4x=5y => x/5=y/4=>x2/25=y2/16
ta có:
x2/25=y2/16=x2-y2/25-16=1/9
x^2/25=1/9=>x^2=25/9=>x=5/3
y^2/16=1/9=>y^2=16/9=>y=4/3
tích của chúng bằng:5/3*4/3=20/9
bài 2: giải các phương trình sau:
a. x -23/24 +x-23/25 = x -23/26 +x - 23/27
b. (x +2/98 +1) +(x +3/97 +1)=(x +4/96 +1) +(x +5/95 +1)
c. x+1/2004 + x+2/2003= x+3/2002 +x+4 /2001
d. 201 -x/99 + 203 -x/97 +205 -x/95 +3 =0
Bài 6 : Tính hợp lí
1 . (-232)+55+(-63)+45
2 . (-205)+21+205+75
3 . 131+269+(-59)+(-131)
4 . (-196)+189+20+(-604)+(-199)
5 . (-170)+43+(-143)
6 . (-43)+(-17)+(-25)
7 . (-249)+121+I-29I+(-121)
8 . (-47)+(-139)+47+169
9 . (-13)+(-7)+(-75)
10 . (-9)+37+(-11)
11 . 12+(-23)+53
12 . (-3)+(-25)+23
13 . (-26)+10+(-14)
14 . (-13)+6+(-37)+14
15 . (-11)+(-9)+5+25
16 . (-12)+(-18)+8
17 . 315+[135+(-315)+(-35)]
18 . 815+[95+(-915)+(-45)]
19 . 5+(-7)+9+(-11)+13+(-15)
20 . (-10)+12+(-14)+16+(-18)+20
Tìm x liên quan đến lũy thừa:
1, \(\left(3x-\dfrac{1}{5}\right)^2=\left(\dfrac{-3}{25}\right)^2\)
2, \(\left(2x-\dfrac{1}{3}\right)^2=\left(\dfrac{-2}{9}\right)^2\)
3, \(\left(\dfrac{1}{3}-x\right)^2=\dfrac{9}{25}\)
4, \(\left(5-x\right)^2=25\)
1: \(\left(3x-\dfrac{1}{5}\right)^2=\left(-\dfrac{3}{25}\right)^2\)
=>3x-1/5=3/25 hoặc 3x-1/5=-3/25
=>3x=8/25 hoặc 3x=2/25
=>x=8/75 hoặc x=2/75
2: \(\left(2x-\dfrac{1}{3}\right)^2=\left(-\dfrac{2}{9}\right)^2\)
=>2x-1/3=2/9 hoặc 2x-1/3=-2/9
=>2x=5/9 hoặc 2x=1/9
=>x=5/18 hoặc x=1/18