Nếu:
17 + 3 = 30
23 + 5 = 37
32 + 9 = 54
Thì
38 + 8 = ?
Câu 1 : thực hiện phép tính ( tính hợp lí nếu có thể ) A, 3/5 + -4/9 B, 3/5 + 2/5 . 15/8 C, 7/2 . 8/13 + 8/13 . -5/2 + 8/13 D, -5/17 . -9/23 + 9/23 . -22/17 + 11 9/23 Lưu ý : 11 9/23 là hỗn số
`a)3/5+(-4/9)`
`=3/5-4/9`
`=27/45-20/45`
`=7/45`
`b)3/5+2/5 . 15/8`
`=3/5 + 30/40`
`=3/5+3/4`
`=12/20+15/20`
`=27/20`
`c)7/2 . 8/13 + 8/13 . (-5/2)`
`=8/13 . (7/2 +(-5)/2)`
`=8/13 . 1`
`=8/13`
`d)-5/17 . (-9/23)+9/23 . (-22/17) + 11 9/23`
`=-5/17 . (-9/23) + 9/23 . (-1) . 22/17 + 11 + 9/23`
`=-5/17 . (-9/23) + (-9/23) . 22/17+11+9/23`
`= -9/23 ( -5/17 + 22/17)+11+9/23`
`= - 9/23 . 1+11+9/23`
`=-9/23+11+9/23`
`=(-9/23+9/23)+11`
`=0+11`
`=11`
a: =27/45-20/45=7/45
b: =3/5+30/40
=3/5+3/4
=12/20+15/20
=27/20
c: =8/13(7/2-5/2+1)=8/13*2=16/13
d: =9/23*5/17-9/23*22/17+11+9/23
=-9/23+11+9/23
=11
Tính nhẩm:
8 + 9 = ..... | 9 + 8 = ..... | 17 − 8 = ..... | 17 − 9 = ..... |
5 + 7 = ..... | 7 + 5 = ..... | 12 − 5 = ..... | 12 − 7 = ..... |
3 + 8 = ..... | 8 + 3 = ..... | 11 − 3 = ..... | 11 − 8 = ..... |
4 + 9 = ..... | 9 + 4 = ..... | 13 − 4 = ..... | 13 − 9 = ..... |
Phương pháp giải:
Tính nhẩm rồi điền số thích hợp vào chỗ trống.
Lời giải chi tiết:
8 + 9 = 17 | 9 + 8 = 17 | 17 − 8 = 9 | 17 − 9 = 7 |
5 + 7 = 12 | 7 + 5 = 12 | 12 − 5 = 7 | 12 − 7 = 5 |
3 + 8 = 11 | 8 + 3 = 11 | 11 − 3 = 8 | 11 − 8 = 3 |
4 + 9 = 13 | 9 + 4 = 13 | 13 − 4 = 9 | 13 − 9 = 4 |
8+9=17 9+8=17 17-8=9 17-9=8
5+7=12 7+5=12 12-5=7 17-7=5
bài 1:
a,1/10*2/9*3/8*4/7*5/6*6/5*7/4*8/3*9/2
b,8/11+4/17-5/11-3/17-65/9-8/17-3/17-6/17
( - 3023 ) - ( 765 - 3023 )
GIÚP MIK NHA
bài 1 Tính:
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
giúp tớ vs ạ. Tớ CẢM ƠN
*tớ thêm một câu nữa ạ
c) 5/9 * 7/13 + 5/9 * 9/13 + 3/13 * -5/9
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
-40/119 + 12/17 × -7/3
-40/119 + -28/17 =-236/119
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
(5/17+12/17)-(10/13+3/13)-11/20
-11/20
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
-40/119 + 12/17 × -7/3
-40/119 + -28/17 =-236/119
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
(5/17+12/17)-(10/13+3/13)-11/20
-11/20
-3/5+8/17+(-5/8)-3/5+9/17
\(=-\dfrac{3}{5}+\dfrac{8}{17}-\dfrac{5}{8}-\dfrac{3}{5}+\dfrac{9}{17}\)
\(=1-\dfrac{6}{5}-\dfrac{5}{8}\)
\(=-\dfrac{1}{5}-\dfrac{5}{8}\)
\(=-\dfrac{33}{40}\)
5/9 × 8/17+ 3/17 : 9/7 - 5/9
\(\dfrac{5}{9}\times\dfrac{8}{17}+\dfrac{3}{17}:\dfrac{9}{7}-\dfrac{5}{9}\\ =\dfrac{40}{153}+\dfrac{7}{51}-\dfrac{5}{9}\\ =\dfrac{61}{153}-\dfrac{5}{9}\\ =\dfrac{-8}{51}\)
5/9 × 8/17+ 3/17 : 9/7 - 5/9
\(\dfrac{5}{9}\times\dfrac{8}{17}+\dfrac{3}{17}:\dfrac{9}{7}-\dfrac{5}{9}=\dfrac{40}{153}+\dfrac{3}{17}\times\dfrac{7}{9}-\dfrac{5}{9}=\dfrac{40}{153}+\dfrac{21}{153}-\dfrac{5}{9}=\dfrac{61}{153}-\dfrac{5}{9}\)
\(=\dfrac{61}{153}-\dfrac{85}{153}=\dfrac{-24}{153}=\dfrac{-8}{51}\)
Ghi kết quả tính:
15 − 7 + 8 = ..... | 6 + 7 − 9 = ..... | 12 − 5 + 7 = ..... |
17 − 9 + 8 = ..... | 9 + 6 − 7 = ..... | 14 − 5 + 3 = ..... |
8 + 8 − 9 = ..... | 17 − 8 + 6 = ..... | 6 + 9 − 9 = ..... |
Phương pháp giải:
Tính nhẩm từ trái sang phải rồi điền kết quả vào chỗ trống.
Lời giải chi tiết:
15 − 7 + 8 = 16 | 6 + 7 − 9 = 4 | 12 − 5 + 7 = 14 |
17 − 9 + 8 = 16 | 9 + 6 − 7 = 8 | 14 − 5 + 3 = 12 |
8 + 8 − 9 = 7 | 17 − 8 + 6 = 15 | 6 + 9 − 9 = 6 |
hihihihiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiihhhhiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiihhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiihhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii
a: =35/17-18/17-9/5+4/5
=1-1=0
b: =-7/19(3/17+8/11-1)
=7/19*18/187=126/3553
c: =26/15-11/15-17/3-6/13
=1-6/13-17/3
=7/13-17/3=-200/39