(15-x)+(x-12)=7-(-8+x)
7/13 x 7/15 - 5/12 x 7/13 + 7/13 x 8/15 = ?
7/13 x 7/15 - 5/12 x 7/13 + 7/13 x 8/15 =7/13x(7/15-5/12+8/15)=7/13x7/12=49/156
12/13×8/15×7/9=........................
........................
Tìm số nguyên x, biết rằng
a . x + − 8 = − ( − 7 ) b . − − 30 − x = − 13 c . x − 8 = − 10 d . − − x + − 15 − − 12 = 0 e . x − − 15 − 7 = − − 9 + − 5 f . 15 − x + 17 = 13 − − 21 g . x = 3 h . x + 2 − 25 = − 5
x-(-7)=-8+(-2)
x+(12-15)=/-3/-7
(12-x )-(-10)=-25
(-20)-(15-x )=-50
a) x - (-7) = -8 + (-2)
x + 7 = -8 - 2
x + 7 = -10
x = -10 - 7
x = -17
b) x + (12 - 15) = /-3/ - 7
x + (-3) = 3 - 7
x - 3 = -4
x = -4 + 3
x = -1
c) (12 - x) - (-10) = -25
(12 - x) + 10 = -25
12 - x = -25 - 10
12 - x = -35
x = 12 - (-35)
x = 12 + 35 = 47
d) (-20) - (15 - x) = -50
15 - x = -20 - (-50)
15 - x = -20 + 50
15 - x = -30
x = 15 - (-30)
x = 15 + 30
x = 45
Tìm x biết:
a, (x + 15)÷8 = 7
b, (x - 23)÷8 = 12
c, 24 = (x + 5)÷5
d, (x - 8)÷7 = 11
a, x-(-7)=-8+(-2) b, x+(12-15)=/-3/-7
c, (12-x )-(-10)=-25
d, (-20)-(15-x )=-50
Tính
a, -(-5)-(+7)+(+3)+(-8)
b, -(-15)-|-10|+|-9|-|5|
c, 14-(-13)-(17)+(-12)
d, -|-14| + |-10| - (-12) + (-8)
e, -(-11) + (-15) + (13) - 21
Bài 2 tìm x
1, -x + 20 = - (-15) - (8) + 13
2, -(-10) + x = -13 + (-9) + (-6)
3, 8-(-12) + 10 = - (-14) - x
4. - (+12) + (-x) - (-3) = 5 - (-7)
5. 14 - x + (-10) = - (-9) + (+15)
6. 12 - (-17) + (-3) = -5 + x
7. X - (-19) - (+32) = 14 - (+16)
8. X - |-15| - |7| = - (-9) + |-5|
9. 15 - x + 17 = 13 - (-21)
10. - |-5| - (-x) +4 = 3 - (-25)
Mọi NGƯỜI GIẢI GIÚP MÌNH VỚI MK CẦN GẤP, MỌI NGƯỜI GHI RÕ CÁCH LÀM RA NHÉ! CẢM ƠN MỌI NGƯỜI
Bạn ơi bạn làm đc bao nhiêu thì làm phụ mình nhé
bài1
a,
5 - 7 + 3 +(-8)
= -2 + 3 + ( - 8)
= 1 + (-8)= -7
a; - (-5) - (+7) + (+3) + (-8)
= 5 - 7 + 3 - 8
= (5 + 3 - 8) - 7
= (8 - 8) - 7
= 0 - 7
= - 7
Tính nhanh :
8/15 + 5/12 - 7/15 - 1/12
9/5 : 7/6 + 3/2 : 7/6 -8/5 x 6/7
0.987 x 3.4 + 0.987 + 5.6 x 0.987
5/6 + 5/8 + 3/4
12/15 + 3 + 3/5
4/3 x 7/8 x 5
8/9 x 6/5 : 3
7/12 + 5/8 x 4/3 - 3/4
(8/5 - 7/6) : 13/15 + 1/4
1) so sánh phân số
a) -8/12 và -3/-4 b)-56 /24 và 7/3 c) -4/25 và 15/-13
2) tính
a) 3/5 x 20/ -9
b)4/15 + -3/2 +8/-5
c) 19/35 x -38/7
d) -7/12 x 13/14 +1/14 x (-7) /12
Bài 1:
a: -8/12<0<-3/-4
b: -56/24<0<7/3
c: 4/25<1<15/13
=>-4/25>-15/13
Bài 2:
a: =-60/45=-4/3
b: =4/15-3/2-8/5=8/30-45/30-48/30=-85/30=-17/6
\(\frac{x+12}{7}+\frac{x+4}{15}+\frac{x+6}{13}=\frac{x+8}{11}+\frac{x+10}{9}+\frac{x+12}{7}\)
=>\(\left(\frac{x+12}{7}+1\right)+\left(\frac{x+4}{15}+1\right)+\left(\frac{x+6}{13}+1\right)=\left(\frac{x+8}{11}+1\right)+\left(\frac{x+10}{9}+1\right)+\left(\frac{x+12}{7}+1\right)\)
=> \(\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}=\frac{x+19}{11}+\frac{x+19}{9}+\frac{x+19}{7}\)
=> \(\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}-\frac{x+19}{11}-\frac{x+19}{9}-\frac{x+19}{7}=0\)
\(\Rightarrow\left(x+19\right)\left(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\right)=0\)
=> x + 19 = 0 Vì \(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\ne0\)
=> x = - 19
Bài làm:
Ta có: \(\frac{x+12}{7}+\frac{x+4}{15}+\frac{x+6}{13}=\frac{x+8}{11}+\frac{x+10}{9}+\frac{x+12}{7}\)
\(\Leftrightarrow\left(\frac{x+12}{7}+1\right)+\left(\frac{x+4}{15}+1\right)+\left(\frac{x+6}{13}+1\right)-\left(\frac{x+8}{11}+1\right)-\left(\frac{x+10}{9}+1\right)-\left(\frac{x+12}{7}+1\right)=0\)
\(\Leftrightarrow\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}-\frac{x+19}{11}-\frac{x+19}{9}-\frac{x+19}{7}=0\)
\(\Leftrightarrow\left(x+19\right)\left(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\right)=0\)
\(\Leftrightarrow\left(x+19\right)\left(\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}\right)=0\)
Mà \(\hept{\begin{cases}\frac{1}{15}< \frac{1}{11}\\\frac{1}{13}< \frac{1}{9}\end{cases}\Rightarrow}\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}< 0\)
\(\Rightarrow x+19=0\)
\(\Rightarrow x=-19\)
\(\frac{x+12}{7}+\frac{x+4}{15}+\frac{x+6}{13}=\frac{x+8}{11}+\frac{x+10}{9}+\frac{x+12}{7}\)
\(\Leftrightarrow\left(\frac{x+12}{7}+1\right)+\left(\frac{x+4}{15}+1\right)+\left(\frac{x+6}{13}+1\right)=\left(\frac{x+8}{11}+1\right)+\left(\frac{x+10}{9}+1\right)+\left(\frac{x+12}{7}+1\right)\)
\(\Leftrightarrow\frac{x+12+7}{7}+\frac{x+4+15}{15}+\frac{x+6+13}{13}=\frac{x+8+11}{11}+\frac{x+10+9}{9}+\frac{x+12+7}{7}\)
\(\Leftrightarrow\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}=\frac{x+19}{11}+\frac{x+19}{9}+\frac{x+19}{7}\)
\(\Leftrightarrow\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}-\frac{x+19}{11}-\frac{x+19}{9}-\frac{x+19}{7}=0\)
\(\Leftrightarrow\left(x+19\right)\left(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\right)=0\)
Vì \(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\ne0\)
\(\Rightarrow x+19=0\Leftrightarrow x=-19\)