Rút gọn
a) 10+5/4*5
b) 2^2*9/27*2
1. Rút Gọn
a)√6-2√5
b)√8+2√7
2 Tính
a) √(√10-3)2 -√10
b)√(5+√7)2 - √8-2√7
\(1,\)
\(a,\sqrt{6-2\sqrt{5}}=\sqrt{\sqrt{5^2}-2.\sqrt{5}.1+1}=\sqrt{\left(\sqrt{5}-1\right)^2}=\left|\sqrt{5}-1\right|=\sqrt{5}-1\)
\(b,\sqrt{8+2\sqrt{7}}=\sqrt{\sqrt{7^2}+2.\sqrt{7}.1+1}=\sqrt{\left(\sqrt{7}+1\right)^2}=\left|\sqrt{7}+1\right|=\sqrt{7}+1\)
\(2,\)
\(a,\sqrt{\left(\sqrt{10}-3\right)^2}-\sqrt{10}\)
\(=\left|\sqrt{10}-3\right|-\sqrt{10}\)
\(=\sqrt{10}-\sqrt{10}-3\)
\(=-3\)
\(b,\sqrt{\left(5+\sqrt{7}\right)^2}-\sqrt{8-2\sqrt{7}}\)
\(=\left|5+\sqrt{7}\right|-\sqrt{\left(\sqrt{7}-1\right)^2}\)
\(=5+\sqrt{7}-\left|\sqrt{7}-1\right|\)
\(=5+\sqrt{7}-\sqrt{7}+1\)
\(=6\)
Rút gọn
a) 20 - 12 . 20/ -30 - 30 . 10
b) 11^9 . 3^15 . 27/ 3^10 .11^11. 3^8
Em cố gắng gõ latex nha
a: \(=\dfrac{20\left(1-12\right)}{30\left(-1-10\right)}=\dfrac{2}{3}\)
b: \(=\dfrac{11^9\cdot3^{18}}{3^{18}\cdot11^{11}}=\dfrac{1}{121}\)
Rút gọn
a) 20 - 12 . 20/ -30 - 30 . 10
b) 11^9 . 3^15 . 27/ 3^10 .11^11. 3^8
a: \(=\dfrac{20\left(1-12\right)}{30\left(-1-10\right)}=\dfrac{20}{30}=\dfrac{2}{3}\)
b: \(=\dfrac{11^9\cdot3^{18}}{3^{10}\cdot11^{11}\cdot3^8}=\dfrac{1}{121}\)
tính rồi rút gọn
a)2-1/4
b)7/9-4/9
c)15/21-4/7
a: =8/4-1/4=7/4
b: =3/9=1/3
c: =5/7-4/7=1/7
a,\(\dfrac{7}{4}\)
b,\(\dfrac{1}{3}\)
c,\(\dfrac{1}{7}\)
Thực hiện phép tính:
a, (8.5^7 - 5^5 +5^6) : 5^5
b, (9^30 - 27^19) : 3^57 + (125^9 - 25^12) : 5^24
c, (10^12 + 5^11 . 2^9 - 5^13 - 2^8) : 4 . 5^5 . 10^6
a: Ta có: \(\left(8\cdot5^7+5^6-5^5\right):5^5\)
\(=8\cdot5^2+5-1\)
\(=200+4=204\)
b: Ta có: \(\left(9^{30}-27^{19}\right):3^{57}+\left(125^9-25^{12}\right):5^{24}\)
\(=3^{60}:3^{57}-3^{57}:3^{57}+5^{27}:5^{24}-5^{24}:5^{24}\)
\(=27-1+125-1\)
=150
a. (8,57 - 55 + 56) : 55
= (8,57 : 55) - (55 : 55) + (56 : 55)
= 1,72 - 1 + 5
= 2,89 - 1 + 5
= 6,89
b. (930 - 2719) : 357 + (1259 - 2512) : 524
= (930 : 357) - (2719 : 357) + (1259 : 524) - (2512 : 524)
= 33 - 1 + 125 - 1
= 27 - 1 + 125 - 1
= 150
c. (1012 + 511 . 29 - 513 - 28) : 4 . 55 . 106
= (1012 + 2,5 , 1010 - 513 - 28) : 1,25 . 1010
= (1012 : 1,25 . 1010) + (2,5 . 1010 : 1,25 . 1010) - (513 : 1,25 . 1010) - (28 : 1,25 . 1010)
= 80 + 2 - \(\dfrac{25}{256}\) - \(\dfrac{1}{48828125}\)
= 81,90234373 \(\approx\) 82
Bài 1: Cặp phân số sau có bằng nhau không?
a) -4/3 và 12/9
b) -2/3 và -6/8
Bài 2: Tìm x,y biết
a)x/-3=2/y
b) x/-9=-8/y=-10/15
Bài 3: Rút gọn
a) -24/78
b)19.25/28.95
c) 19-19.8/8-27
Bài 4: So sánh
a) -2/3 và 5/-8
b) 398/-412 và -25/-137
c) -14/21 và 60/72
Bài 5: a) Cho A= 5/n-3 Tìm điều kiện của n để A là phân số
b) Cho B= 2n+7/n+3
Tìm giá trị của n để B là sô nguyên
1:
a: Vì \(\dfrac{-4}{3}=\dfrac{-4\cdot3}{3\cdot3}=\dfrac{-12}{9}=\dfrac{12}{9}\\ \Rightarrow\dfrac{-4}{3}=\dfrac{12}{9}\)
b: Vì : \(-2\cdot3=-6\\ -6\cdot8=-48\)
nên 2 p/s ko bằng nhau
rút gọn
a/\(\sqrt{12}+3\sqrt{27}-\sqrt{300}\)
b/ \(\sqrt{\left(1-\sqrt{2}\right)^2}-\sqrt{\left(\sqrt{2+3}\right)^2}\)
\(a,=2\sqrt{3}+9\sqrt{3}-10\sqrt{3}=\sqrt{3}\\ b,=\left|1-\sqrt{2}\right|+\sqrt{5}=\sqrt{2}-1+\sqrt{5}\)
a)\(\sqrt{12}+3\sqrt{27}-\sqrt{300}=2\sqrt{3}+9\sqrt{3}-10\sqrt{3}=\sqrt{3}\)
b) \(\sqrt{\left(1-\sqrt{2}\right)^2}-\sqrt{\left(\sqrt{2}+3\right)^2}=\left|1-\sqrt{2}\right|-\left|\sqrt{2}+3\right|=\sqrt{2}-1-\sqrt{2}-3=-4\)
rút gọn
a) A=\(\sqrt{4-2\sqrt{3}}-\sqrt{4+2\sqrt{3}}\)
b) B=\(\sqrt{11-6\sqrt{2}}-\sqrt{3-2\sqrt{2}}\)
c) C=\(\left(\sqrt{3}+\sqrt{5}\right)\times\sqrt{7-2\sqrt{10}}\)
lm nhanh giúp mk nhé
a) \(A=\sqrt{4-2\sqrt{3}}-\sqrt{4+2\sqrt{3}}\)
\(=\sqrt{\left(\sqrt{3}\right)^2-2.\sqrt{3}.1+1^2}-\sqrt{\left(\sqrt{3}\right)^2+2.\sqrt{3}.1+1^2}\)
\(=\sqrt{\left(\sqrt{3}-1\right)^2}-\sqrt{\left(\sqrt{3}+1\right)^2}=\left|\sqrt{3}-1\right|-\left|\sqrt{3}+1\right|\)
\(=\sqrt{3}-1+-\sqrt{3}-1=-2\)
b) \(B=\sqrt{11-6\sqrt{2}}-\sqrt{3-2\sqrt{2}}\)
\(=\sqrt{3^2-2.3.\sqrt{2}+\left(\sqrt{2}\right)^2}-\sqrt{\left(\sqrt{2}\right)^2-2.\sqrt{2}.1+1^2}\)
\(=\sqrt{\left(3-\sqrt{2}\right)^2}-\sqrt{\left(\sqrt{2}-1\right)^2}=\left|3-\sqrt{2}\right|-\left|\sqrt{2}-1\right|\)
\(=3-\sqrt{2}-\sqrt{2}+1=4-2\sqrt{2}\)
c) \(C=\left(\sqrt{3}+\sqrt{5}\right)\sqrt{7-2\sqrt{10}}\)
\(=\left(\sqrt{5}+\sqrt{3}\right)\sqrt{\left(\sqrt{5}\right)^2-2.\sqrt{5}.\sqrt{2}+\left(\sqrt{2}\right)^2}\)
\(=\left(\sqrt{5}+\sqrt{3}\right)\sqrt{\left(\sqrt{5}-\sqrt{2}\right)^2}=\left(\sqrt{5}+\sqrt{3}\right)\left|\sqrt{5}-\sqrt{2}\right|\)
\(=\left(\sqrt{5}+\sqrt{3}\right)\left(\sqrt{5}-\sqrt{2}\right)=5-\sqrt{10}+\sqrt{15}-\sqrt{6}\)
bài 4: rút gọn
A= 1+5+5^2+5^3+5^4 + ........ +5^99 + 5^100
B= 1-5+5^2-5^3 + ...... - 3^99 + 5^100
Câu a)
Câu b) Đề bài sai.