Tinh
√27×(1-√3) ÷3√75
Tinh
√27×(1-√3)binh phuong ÷3√75
Kết quả của phép tinh √12−√27 + √75 bằng A)-3√3 B) 3√3. C)5√3. D)4√3.
Lời giải:
$\sqrt{12}-\sqrt{27}+\sqrt{75}=\sqrt{2^2.3}-\sqrt{3^2.3}+\sqrt{5^2.3}$
$=2\sqrt{3}-3\sqrt{3}+5\sqrt{3}=(2-3+5)\sqrt{3}=4\sqrt{3}$
Đáp án D
1 Tinh bang cach thuan tien nhat
a) 9 gio 36 phut : 3 -1,25 gio:
b) 2 gio 27 phut :3 +3 gio 33phut :3 +1 gio 12 phut *2.
c) ( 3 gio 45 phut + 3, 75 gio ): 2 - 1, 5 : 2.
a) 1 giờ 57 phút
b) 4 giờ 24 phút
c) 2,875 giờ
nhớ k đó
b) Viet tich sau duoi dang mot luy thua :
2 . 2 . 2 . 3 .3 . 62 . 3
c) Tinh 27 . 75 . +25 . 27 - 150
Ai biet giai giup minh voi nhe!
b) 2.2.2.3.3.62.3 = 2.2.2.3.3.6.6.3 = 2.2.2.3.3.3.2.3.2.3 = 25.35
Thực hiện phép tinh:
a)\(\sqrt{12}+2\sqrt{27}+3\sqrt{75}-9\sqrt{48}\)
b) \(2\sqrt{3}.\left(\sqrt{27}+2\sqrt{48}-\sqrt{75}\right)\)
c) \(\left(1+\sqrt{3}-\sqrt{2}\right).\left(1+\sqrt{3}+\sqrt{2}\right)\)
d) \(\sqrt{13-\sqrt{160}}-\sqrt{53+4\sqrt{90}}\)
a/\(\sqrt{12}+2\sqrt{27}+3\sqrt{75}-9\sqrt{48}\)
\(=2\sqrt{3}+6\sqrt{3}+15\sqrt{3}-36\sqrt{3}=-13\sqrt{3}\)
b/ \(2\sqrt{3}\left(\sqrt{27}+2\sqrt{48}-\sqrt{75}\right)\)
\(=2\sqrt{3}\left(3\sqrt{3}+8\sqrt{3}-5\sqrt{3}\right)\)
\(=2\sqrt{3}\cdot6\sqrt{3}=2\cdot6\cdot3=36\)
c/ \(\left(1+\sqrt{3}-\sqrt{2}\right)\left(1+\sqrt{3}+\sqrt{2}\right)\)
\(=\left(1+\sqrt{3}\right)^2-\left(\sqrt{2}\right)^2\)
\(=1+2\sqrt{3}+3-2\)
\(=2+2\sqrt{3}\)
d/ \(\sqrt{13-\sqrt{160}}-\sqrt{53+4\sqrt{90}}\)
\(=\sqrt{13-4\sqrt{10}}-\sqrt{53+4\sqrt{90}}\)
\(=\sqrt{8-4\sqrt{10}+5}-\sqrt{45+12\sqrt{10}+8}\)
\(=\sqrt{\left(2\sqrt{2}\right)^2-2\cdot2\sqrt{2\cdot5}+\left(\sqrt{5}\right)^2}-\sqrt{\left(3\sqrt{5}\right)^2+2\cdot3\cdot2\sqrt{5\cdot2}+\left(2\sqrt{2}\right)^2}\)
\(=\sqrt{\left(2\sqrt{2}-\sqrt{5}\right)^2}-\sqrt{\left(3\sqrt{5}+2\sqrt{2}\right)^2}\)
\(=2\sqrt{2}-\sqrt{5}-3\sqrt{5}-2\sqrt{2}\)
\(=-4\sqrt{5}\)
#)Giải :
\(\sqrt{12}+2\sqrt{27}+3\sqrt{75}-9\sqrt{48}=2\sqrt{3}+6\sqrt{3}+15\sqrt{3}-36\sqrt{3}=-13\sqrt{3}\)
tinh 27 . 75 +25 . 27 - 150
Bằng 2550 ík
Thuc hien phep tinh ( tinh nhanh neu co the )
a) 27 . ( 58 - 43 ) + 43 . ( 27 + 58 )
b) 66 . ( 34 - 75 ) - 34 . ( 66 + 75 )
Minh can gap !!!!!!
a , 27 . ( 58 - 43 ) + 43 . ( 27 + 58 ) b . 66 . ( 34 - 75 ) - 34 . ( 66 + 75 )
= 27 . 10 + 43 . 85 = 66 . ( 34 - 75 ) + ( -34 ) . ( 66 + 75 )
= 270 + 3755 = [ 66 . 75 + 66 + 75 ] . 34 . ( - 34 )
= 4025 0
k và kb nếu có thể
√75 -√[5+1÷3] +[9÷2]×√[2+2÷3]+2√27
\(2\sqrt{\dfrac{16}{3}}-3\sqrt{\dfrac{1}{27}}-6\sqrt{\dfrac{4}{75}}\)
√163 ≈ 12.767 √127 ≈ 11.269 √475 ≈ 21.794
2√163 - 3√127 - 6√475 ≈ 2(12.767) - 3(11.269) - 6(21.794)
≈ 25.534 - 33.807 - 130.764
≈ -138.037
Vậy giá trị của biểu thức 2√163 - 3√127 - 6√475 là -138.037.
\(=2\cdot\dfrac{4}{\sqrt{3}}-3\cdot\dfrac{1}{3\sqrt{3}}-6\cdot\dfrac{2}{5\sqrt{3}}\)
\(=\dfrac{8}{\sqrt{3}}-\dfrac{1}{\sqrt{3}}-\dfrac{12}{5\sqrt{3}}=\dfrac{7}{\sqrt{3}}-\dfrac{12}{5\sqrt{3}}\)
\(=\dfrac{1}{\sqrt{3}}\left(7-\dfrac{12}{5}\right)=\dfrac{23}{5\sqrt{3}}=\dfrac{23\sqrt{3}}{15}\)