Tính
47 - [(39 . 24 - 52 . 42) : 14]
(217 + 172).(915 - 159)(42 - 24)
Giúp em với!!!!!!!!!!!!!!!!
(217+172).(915-315).(24-42)
đáp án bằng 0
Vì ta phân tích \(2^4\) bằng \(4^2\) nên khi ta trừ cho nhau =0
Mặt khác tất cả các số nhân với nhau bằng 0
\(\left(2^{17}+17^2\right).\left(9^{15}-3^{15}\right).\left(2^4-4^2\right)\\ =\left(2^{17}+17^2\right).\left(9^{15}-3^{15}\right).\left(16-16\right)\\ =\left(2^{17}+17^2\right).\left(9^{15}-3^{15}\right).0=0\)
Thực hiện các phép tính sau bằng cách hợp lý.
a) (217 + 172).(915 – 315).(24 – 42)
b) (82017 – 82015) : (82104.8)
a) (217 + 172).(915 – 315).(24 – 42)
= (217 + 172).(915 – 315).(16 - 16)
= 0
Vậy giá trị cần tìm là: 0
b) (82017 – 82015) : (82104.8)
= 82015.(82- 1) : 82015
= 64 – 1
= 63
Vậy giá trị cần tìm là: 63
Thực hiện các phép tính sau bằng cách hợp lý.
a) (217 + 172).(915 – 315).(24 – 42)
b) (82017 – 82015) : (82104.8)
a) (217+ 172).(915– 315).(24 – 42)
= (217 + 172).(915 – 315).(16 - 16)
= 0
Vậy giá trị cần tìm là: 0
b) (82017– 82015) : (82104.8)
= 82015.(82- 1) : 82015
= 64 – 1
= 63
Vậy giá trị cần tìm là: 63
tính bằng cách hợp lý
(217+172).(915-315).(24-42)
(71997-71995):(71994.7)
(12+23+34+45).(13+23+3343).(38-812)
(28+83):(25.23)
\(\left(2^{17}+7^2\right).\left(9^{15}-3^{15}\right).\left(2^4-4^2\right)\)
\(=\left(2^{17}+7^2\right).\left(9^{15}-3^{15}\right).\left(16-16\right)\)
\(=\left(2^{17}+7^2\right).\left(9^{15}-3^{15}\right).0\)
\(=0\)
-------------------------------------------------
\(\left(7^{1997}-7^{1995}\right):\left(7^{1994}.7\right)\)
\(=\left[7^{1995}\left(7^2-1\right)\right]:7^{1995}\)
\(=7^{1995}.48:7^{1995}\)
\(=48\)
-------------------------------------------------
\(\left(1^2+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left(3^8-81^2\right)\)
\(=\left(1^2+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).\left(6561-6561\right)\)
\(=\left(1^2+2^3+3^4+4^5\right).\left(1^3+2^3+3^3+4^3\right).0\)
\(=0\)
-------------------------------------------------
\(\left(2^8+8^3\right):\left(2^5.2^3\right)\)
\(=\left[2^8+\left(2^3\right)^3\right]:2^8\)
\(=\left(2^8+2^9\right):2^8\)
\(=2^8.\left(1+2\right):2^8\)
\(=2^8.3:2^8\)
\(=3\)
\((2^{17}+17^{2}).(9^{15}-3^{15}).(2^{4}-4^{2})\)
\(=(2^{17}+17^{2}).(9^{15}-3^{15}).(16-16)\)
\(=(2^{17}+17^{2}).(9^{15}-3^{15}).0\)
\(=0\)
\((7^{1997}-7^{1995}):(7^{1994}.7)\)
\(=(7^{1997}-7^{1995}):7^{1995}\)
\(=7^{1997}:7^{1995}-7^{1995}:7^{1995}\)
\(=7^{2}-1=49-1=48\)
\(1^{2}+2^{3}+3^{4}+4^{5}).(1^{3}+2^{3}+3^{3}+4^{3}).(3^{8}-81^{2})\)
\(=(1^{2}+2^{3}+3^{4}+4^{5}).(1^{3}+2^{3}+3^{3}+4^{3}).(6561-6561)\)
\(=(1^{2}+2^{3}+3^{4}+4^{5}).(1^{3}+2^{3}+3^{3}+4^{3}).0\)
\(=0\)
\((2^{8}+8^{3}):(2^{5}.2^{3})\)
\(=[2^{8}+(2^{3})^{3}]:2^{8}\)
\(=(2^{8}+2^{9}):2^{8}\)
\(=2^{8}:2^{8}+2^{9}:2^{8}\)
\(=1+2=3\)
Bài toán 4: Thực hiện các phép tính sau bằng cách hợp lý.
a) (217+ 172).(915– 315).(24 – 42)
b) (82017– 82015) : (82104.8)
c) (13+ 23+ 34 + 45).(13 + 23 + 33 + 43).(38 – 812)
d) (28+ 83) : (25.23)
a: Ta có: \(\left(2^{17}+17^2\right)\cdot\left(9^{15}-3^{15}\right)\cdot\left(2^4-4^2\right)\)
\(=\left(2^{17}+17^2\right)\cdot\left(9^{15}-3^{15}\right)\cdot\left(16-16\right)\)
=0
b: Ta có: \(\dfrac{8^{2017}-8^{2015}}{8^{2104}\cdot8}\)
\(=\dfrac{8^{2015}\cdot\left(8^2-1\right)}{8^{2105}}\)
\(=\dfrac{1\cdot63}{8^{90}}\)+
c: Ta có: \(\left(1^3+2^3+3^4+4^5\right)\cdot\left(1^3+2^3+3^3+4^3\right)\cdot\left(3^8-81^2\right)\)
\(=\left(1^3+2^3+3^4+4^5\right)\cdot\left(1^3+2^3+3^3+4^3\right)\cdot\left(3^8-3^8\right)\)
=0
d: Ta có: \(\left(2^8+8^3\right):\left(2^5\cdot2^3\right)\)
\(=\dfrac{2^8+2^9}{2^8}\)
=3
(2¹⁷ + 17²) . (9¹⁵ - 3¹⁵) . (2⁴ - 4²)
= (2¹⁷ + 17²) . (9¹⁵ - 3¹⁵) . (16 - 16)
= (2¹⁷ + 17²) . (9¹⁵ - 3¹⁵) . 0
= 0
Bài toán : Thực hiện các phép tính sau bằng cách hợp lý.
a. (217 + 172)x(915 – 315)x(24 – 42)
b. (82017 – 82015) : (82104.8)
c. (13 + 23 + 34 + 45).(13 + 23 + 33 + 43).(38 – 812)
d. (28 + 83) : (25.23)
Tính hợp lý (nếu có thể)
a) A = (217+172).(915 – 330 ).(24 – 322)
b) B =(28.83) : (25.23)
c) C = 644.165 : 420
\(a,A=\left(2^{17}+17^2\right)\left(9^{15}-3^{30}\right).\left(2^4-32^2\right)\)
\(\Rightarrow A=\left(2^{17}+17^2\right)\left(3^{30}-3^{30}\right).\left(2^4-32^2\right)\)
\(\Rightarrow A=\left(2^{17}+17^2\right).0.\left(2^4-32^2\right)\)
\(\Rightarrow A=0.\)
\(\Rightarrow B=\left(2^8.8^3\right):\left(2^5.2^3\right)\)
\(\Rightarrow B=\left(2^8.2^9\right):\left(2^5.2^3\right)\)
\(\Rightarrow B=2^{17}:2^8\)
\(\Rightarrow B=2^9\)
\(\Rightarrow B=512\)
\(c,C=64^4.16^5:4^{20}\)
\(\Rightarrow C=2^{24}.2^{20}:2^{40}\)
\(\Rightarrow C=2^4\)
\(\Rightarrow C=16\)
a: \(A=\left(2^{17}+17^2\right)\cdot\left(2^4-32^2\right)\cdot\left(3^{30}-3^{30}\right)=0\)
b: \(B=\dfrac{2^8\cdot2^9}{2^5\cdot2^3}=2^9\)
c: \(C=2^{24}\cdot2^{20}:2^{40}=2^4=16\)
g) (15 + 37) + (52 – 37 – 17) h) (38 – 42 +14) - (38 – 42 - 15) i) (27 + 65 ) + (346 - 27- 65) k) - (27 + 65) - (346 – 27 - 65) l) (42 – 69 + 17) - (42 + 17) m) 24. (16 - 5) – 16. (24 – 5 ) n) (-12). 47 – 12 . 52 + (-12) p) 51 . (69 - 25) – 69. (51 - 25) |
g) (15 + 37) + (52 – 37 – 17) = 15 + 37 + 52 – 37 – 17 = 15 + 52 – 17 = 50 h) (38 – 42 +14) - (38 – 42 - 15) = 38 – 42 +14 - 38 + 42 + 15 = 14 + 15 = 29 i) (27 + 65 ) + (346 - 27- 65) = 27 + 65 + 346 - 27- 65 = 346 k) - (27 + 65) - (346 – 27 - 65) = -27 - 65 - 346 + 27 + 65 = -346 l) (42 – 69 + 17) - (42 + 17) = 42 – 69 + 17 - 42 - 17 = – 69 m) 24. (16 - 5) – 16. (24 – 5 ) = 24. 16 - 24 . 5 - 16 . 24 + 16. 5 = - 24 . 5 + 16. 5 = -8 . 5 = -40 n) (-12). 47 – 12 . 52 + (-12) = -12 (47 - 52 + 1) = -12 . (-4) = 48 p) 51 . (69 - 25) – 69. (51 - 25) = 51 . 69 - 51 . 25 – 69. 51 + 69. 25 = - 51 . 25 + 69. 25 = (- 51+ 69).25 = 450 |
So sánh các phân số mà không cần quy đồng mẫu số:
a)17/52 và 41/120
b)13/14 và 11×12×13+22×24×26+33×36×39/12×13×14+24×26×28+36×39×42