-80-[48+(4-12)²]÷(-2)³
Tính hợp lí
1/ 45. 18 – 5. 9. 28
2/ 54 – 6. (12 + 9)
3/ 23. (16 – 5) – 16. (23 - 5)
4/ 29. (2019 – 13) – 2019. (29 – 13)
5/ 31. (-18) + 31. ( - 80) – 31.2
6/ (-12).48 + (-12). 51 + (-12)
7/ 13.(20 + 22) – 3.(17 + 25)
8/ -48 + 48. (-75) + 48.(-24)
1/ 45. 18 - 5. 9. 28
= 45. 18 - (5. 9) . 28
= 45.18 - 45 .28
= 45. ( 18 - 28)
= 45. ( -10)
= -450
2/ 54 - 6. (12 + 9)
= 54 - 6. 9 + 6. 12
= 54 - 54 + 6. 12
= 0 + 6. 12
= 72
1)\(\sqrt{12}\)\(-\)\(\sqrt{27}\)\(+\)\(\sqrt{48}\)
2)(\(\sqrt{24}+\sqrt{20}-\sqrt{80}\))\(\div\)5
3)2\(\sqrt{27}-\sqrt{\dfrac{16}{3}}\)\(-\)\(\sqrt{48}-\)\(\sqrt{8\dfrac{1}{3}}\)
4) \(\dfrac{1}{\sqrt{5}-\sqrt{3}}\)\(-\)\(\dfrac{1}{\sqrt{5+\sqrt{3}}}\)
\(1,=2\sqrt{3}-3\sqrt{3}+4\sqrt{3}=3\sqrt{3}\\ 2,=\left(2\sqrt{6}+2\sqrt{5}-4\sqrt{5}\right):5=\dfrac{2\sqrt{6}}{5}-\dfrac{2\sqrt{5}}{5}\\ 3,=6\sqrt{3}-\dfrac{4\sqrt{3}}{3}-4\sqrt{3}-\dfrac{5\sqrt{3}}{3}=2\sqrt{3}-\dfrac{9\sqrt{3}}{3}=2\sqrt{3}-3\sqrt{3}=-\sqrt{3}\\ 4,Sửa:\dfrac{1}{\sqrt{5}-\sqrt{3}}-\dfrac{1}{\sqrt{5}+\sqrt{3}}\\ =\dfrac{\sqrt{5}+\sqrt{3}-\sqrt{5}+\sqrt{3}}{\left(\sqrt{5}-\sqrt{3}\right)\left(\sqrt{5}+\sqrt{3}\right)}=\dfrac{2\sqrt{3}}{2}=\sqrt{3}\)
1) \(=2\sqrt{3}-3\sqrt{3}+4\sqrt{3}=3\sqrt{3}\)
2) \(=\left(2\sqrt{6}+2\sqrt{5}-4\sqrt{5}\right)=\dfrac{2\sqrt{6}}{5}+\dfrac{2\sqrt{5}}{5}-\dfrac{4\sqrt{5}}{5}\)
3) \(=6\sqrt{3}-\dfrac{4\sqrt{3}}{3}-4\sqrt{3}-\dfrac{5\sqrt{3}}{3}=2\sqrt{3}-3\sqrt{3}=-\sqrt{3}\)
4) \(=\dfrac{\sqrt{5}+\sqrt{3}-\sqrt{5}+\sqrt{3}}{5-3}=\dfrac{2\sqrt{3}}{2}=\sqrt{3}\)
2*25^6 và 5^12
3*5^48 và 100^16
4*2^60 và 2^40
5*80^13vaf 244^11
rút gọn biểu thức
A=2\(\sqrt{27}\)+5\(\sqrt{12}\)-3\(\sqrt{48}\)
B=\(\sqrt{147}\)+\(\sqrt{75}\)-4\(\sqrt{27}\)
C=3\(\sqrt{2}\)(4-\(\sqrt{2}\))+3(1-2\(\sqrt{2}\))2
D=2\(\sqrt{5}\)-\(\sqrt{125}\)-\(\sqrt{80}\)+\(\sqrt{605}\)
a: \(A=6\sqrt{3}+10\sqrt{3}-12\sqrt{3}=4\sqrt{3}\)
b: \(B=7\sqrt{3}+5\sqrt{3}-12\sqrt{3}=0\)
c: \(=12\sqrt{2}-6+3\left(9-4\sqrt{2}\right)=12\sqrt{2}-6+27-12\sqrt{2}=21\)
d: \(=2\sqrt{5}-5\sqrt{5}-4\sqrt{5}+11\sqrt{5}=4\sqrt{5}\)
A=2^2019 -1 -2-2^2-2^3-....-2^2018
C=8+24+48+80+...+440
E=1-2^2+2^4-2^6+...+2^12-2^14+2^16
0+1+4+9+16+...+1000
1. Tính nhanh nếu có thể :
a) (-25) . (-35) . (-4)
b) 16 - 50 : 5
c) 180 - 80 : (-5) - 12 . (-3)
d) 250 - 200 : [2000 . (12-15)2 + (-2)3]
2. Tìm x, biết :
a) 60 + 2 . (12-x) = - 48
3.
Cho A = 71 + 72 + 73+74+75+76+...+716+717+718.
Chứng tỏ :
a) A \(⋮\) 8
b) A\(⋮\) 57
c) A\(⋮\) 50
d) A \(⋮\) 57
Bài 1:
a. $=(-25)(-4)(-35)=100(-35)=-3500$
b. $=16-10=6$
c. $=180-(-16)-(-36)=180+16+36=232$
d. $=250-200:[1(-3)^2+(-8)]$
$=250-200:(9-8)=250-200=50$
2.
$60+2(12-x)=-48$
$2(12-x)=60-(-48)=60+48=108$
$12-x=108:2=54$
$x=12-54=-42$
Bài 3:
$A=(7+7^2)+(7^3+7^4)+....+(7^{17}+7^{18})$
$=7(1+7)+7^3(7+1)+...+7^{17}(1+7)$
$=(1+7)(7+7^3+....+7^{17})=8(7+7^3+....+7^{17})\vdots 8$
b.
$A=(7+7^2+7^3)+(7^4+7^5+7^6)+...+(7^{16}+7^{17}+7^{18})$
$=7(1+7+7^2)+7^4(1+7+7^2)+....+7^{16}(1+7+7^2)$
$=(1+7+7^2)(7+7^4+....+7^{16})$
$=57(7+7^4+...+7^{16})\vdots 57$
c.
$A=(7+7^2+7^3+7^4)+(7^5+7^6+7^7+7^8)+(7^9+7^{10}+7^{11}+7^{12})+(7^{13}+7^{14}+7^{15}+7^{16})+(7^{17}+7^{18})$
$=7(1+7+7^2+7^3)+7^5(1+7+7^2+7^3)+7^9(1+7+7^2+7^3(+7^{13}(1+7+7^2+7^3)+7^{17}(1+7)$
$=(1+7+7^2+7^3)(7+7^5+7^9+7^{13})+8.7^{17}$
$=400(7+7^5+7^9+7^{13})+8.7^{17}$
Ta thấy $400(7+7^5+7^9+7^{13})\vdots 50$ nhưng $8.7^{17}\not\vdots 50$ nên $A\not\vdots 50$
1. Tính nhanh nếu có thể :
a) (-25) . (-35) . (-4)
b) 16 - 50 : 5
c) 180 - 80 : (-5) - 12 . (-3)
d) 250 - 200 : [2000 . (12-15)2 + (-2)3]
2. Tìm x, biết :
a) 60 + 2 . (12-x) = - 48
3.
Cho A = 71 + 72 + 73+74+75+76+...+716+717+718.
Chứng tỏ :
a) A 8
b) A 57
c) A 50
d) A 57
Bài 1:
a. $=(-25)(-4)(-35)=100(-35)=-3500$
b. $=16-10=6$
c. $180-(-16)-(-36)=180+16+36=196+36=232$
d. $=250-200:[2000.(-3).2-6]$
$=250-200:[2000.(-6)+(-6)]$
$=250-200:[(-6)(2000+1)]=250-200[(-6).2001]$
$=250+200.6.2001=250+2401200=2401450$
Bài 2:
$60+2(12-x)=-48$
$2(12-x)=-48-60=-108$
$12-x=-108:2=-54$
$x=12-(-54)=66$
Bài 3:
Số số hạng của A: $(718-71):1+1=648$
$A=(718+71)\times 648:2=789\times 324$
a. Có: $A=789\times 324=789\times 81\times 4$
$\Rightarrow A\not\vdots 8$ (bạn xem lại đề)
b. $A=789\times 81\times 4\not\vdots 57$ (bạn xem lại đề)
c. $A=789\times 81\times 4\not\vdots 50$
Vậy có vẻ đề câu này sai rồi. Bạn xem lại.
D=√147 +√54 -4√27
A =√112 - 7√(1/7) - 14√(1/28)-21/√7
B = 3√2(4 -√2) + 3(1 - 2√2)^2
C = 2√27 + 5√12 - 3√48
E = (√15 - 2√3)^2 + 12√5
F = 3√50 - 7√8 + 12√18
G = 2√80 - 2√245 + 2√180
H =√28 - 4√63 + 7√112
I =√44 -√176 + 2√275
cái này bấm máy tính là thầy mình k cho đâu =))) phải trình bày ra mà
D=√147 +√54 -4√27
A =√112 - 7√(1/7) - 14√(1/28)-21/√7
B = 3√2(4 -√2) + 3(1 - 2√2)^2
C = 2√27 + 5√12 - 3√48
E = (√15 - 2√3)^2 + 12√5
F = 3√50 - 7√8 + 12√18
G = 2√80 - 2√245 + 2√180
H =√28 - 4√63 + 7√112
I =√44 -√176 + 2√275