tính D bt D= [(-5)+(-12)] +[(-12)+5] +[-5+12]
Tính giá trị của biểu thức a) A = (-10) + ( -34) + ( -54) b) B = 12 + ( -24) + 35 c) C = |- 1 + 2| +| - 2 + 1| + |- 1 + (-2)| d) D = [(-5) + ( -12)] + [( -12) + 5] + [-5 + 12]
tim x số nguyên bt
a. (-12).x=(15).(-4)-12
b.(-5).x+5=(-3).(-8)+6
c.2.(5+3x)+x=31
d.(3x-7)+2.(5-2x)+5x=19
Tính: a) 1/8 - 1/2 b) -11/12 - (-2) c) -1/12 - 1/9 d) -5/9 - (-5)/12
a)=\(-\dfrac{3}{8}\)
b)=\(\dfrac{13}{12}\)
c)=\(-\dfrac{7}{36}\)
d)=\(-\dfrac{5}{36}\)
\(\dfrac{1}{8}-\dfrac{1}{2}=\dfrac{1-4}{8}=\dfrac{-3}{8}.\\ \dfrac{-11}{12}-\left(-2\right)=\dfrac{-11}{12}+2=\dfrac{13}{12}.\\ \dfrac{-1}{12}-\dfrac{1}{9}=\dfrac{-7}{36}.\\ \dfrac{-5}{9}-\dfrac{-5}{12}=\dfrac{-5}{36}.\)
Kết quả của phép tính 3/5 : 4 là: A.12/5 B.12/20 C.3/20 D.12/15
1.tính A.-5/8-7/-12 B.3/4+(-5)/6-11/-12 C.1/6-1/36 D.15/48-(-5)/12 E.-1/7-1/8 F.-5/15-(-3)/25 G.3/4-(-5)/12-7/-24
a: \(=\dfrac{-5}{8}+\dfrac{7}{12}=\dfrac{-15}{24}+\dfrac{14}{24}=\dfrac{-1}{24}\)
b: \(=\dfrac{3}{4}-\dfrac{5}{6}+\dfrac{11}{12}=\dfrac{9}{12}-\dfrac{10}{12}+\dfrac{11}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)
c: \(=\dfrac{6}{36}-\dfrac{1}{36}=\dfrac{5}{36}\)
d: \(=\dfrac{5}{12}+\dfrac{5}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)
e: \(=\dfrac{-8}{56}-\dfrac{7}{56}=\dfrac{-15}{56}\)
f: \(=\dfrac{-5}{15}+\dfrac{3}{25}=\dfrac{-25}{75}+\dfrac{9}{75}=\dfrac{-16}{75}\)
tìm x bt a) 1/2-(3/4-5/6)=1-x b)1/4-x=1/3-1/5 c)5/3-3/4+x=7/12 d)1/4-(1/3-x+5/12)=3-(7/0-1/2 giúp mình nhé
a) 1/2 - (3/4 - 5/6)
<=> 1/2 - (3/4 - 5/6) + x = 1 - x + x
<=> x + 7/12 = 1
<=> x = 1 - 7/12
<=> x = 5/12
=> x = 5/12
b) 1/4 - x = 1/3 - 1/5
<=> 1/4 - x = 5/15 - 3/15
<=> 1/4 - x = 2/15
<=> x = 2/15 - 1/4
<=> x = 7/60
=> x = 7/60
c) 5/3 - 3/4 + x = 7/12
<=> 20/12 - 9/12 + x = 7/12
<=> 11/12 + x = 7/12
<=> x = 7/12 - 11/12
<=> x = -1/3 (sau khi rút gọn)
=> x = -1/3
Tính một cách hợp lí:
a) 10 - 12 - 8;
b) 4 - (-15) - 5 + 6;
c) 2 - 12 - 4 - 6;
d) -45 - 5 - (-12) + 8.
a) 10 – 12 – 8 = 10 – (12 + 8) = 10 - 20 = - 10
b) 4 – (- 15) – 5 + 6 = (4 + 6) – [(-15) + 5)] = 10 – (- 10) = 10 + 10 = 20
c) 2 – 12 – 4 – 6 = (2 – 12) - (4 + 6) = -10 + (- 10) = - 20
d) – 45 – 5 – (- 12) + 8 = - (45 + 5) + (12 + 8) = (- 50) + 20 = - 30
a) 10-12-8=2-12=-10
b) 4-(-15)-5+6=4+15-5+6=10+10=20
c) 2-12-4-6=-10-10=-20
d) -45-5-(-12)+8=-50+12+8=-50+20=-30
tính:
a,9-(-5)-21 b,(-5)+7-12 c,8-(3-6) d,(-4)-(7-12)
Lời giải:
a. $=9+5-21=14-21=-7$
b. $=2-12=-10$
c. $=8-(-3)=8+3=11$
d. $=(-4)-(-5)=-4+5=1$
Thực hiện phép tính:
\(d,\dfrac{-5}{12}+0,75\)
\(e,\dfrac{5}{7}.12\dfrac{1}{2}-\dfrac{5}{7}.5\dfrac{1}{2}\)
\(d,-\dfrac{5}{12}+\dfrac{3}{4}=-\dfrac{5}{12}+\dfrac{9}{12}=\dfrac{4}{12}=\dfrac{1}{3}\)
\(e,\dfrac{5}{7}.\dfrac{25}{2}-\dfrac{5}{7}.\dfrac{11}{2}=\dfrac{5}{7}.\left(\dfrac{25}{2}-\dfrac{11}{2}\right)=\dfrac{5}{7}.7=5\)