Thực hiện các phép tính sau
a) 28 1 2 + 2 5 3
b) 16 5 9 − 12 1 3
Thực hiện phép tính và rút gọn các biểu thức sau
a, P = \(\dfrac{\sqrt{3}+\sqrt{6}}{1+\sqrt{2}}\)
b, Q = (\(\sqrt{75}\) - \(\dfrac{3}{2}\) : \(\sqrt{3}\) - \(\sqrt{48}\)) . \(\sqrt{\dfrac{16}{3}}\)
a) \(P=\dfrac{\sqrt{3}+\sqrt{6}}{1+\sqrt{2}}=\dfrac{\left(\sqrt{3}+\sqrt{6}\right)\left(1-\sqrt{2}\right)}{\left(1+\sqrt{2}\right)\left(1-\sqrt{2}\right)}\)
\(=\dfrac{\sqrt{3}-\sqrt{6}+\sqrt{6}-\sqrt{12}}{1-2}=\sqrt{12}-\sqrt{3}\)
b) \(Q=\left(\sqrt{75}-\dfrac{3}{2}:\sqrt{3}-\sqrt{48}\right)\cdot\sqrt{\dfrac{16}{3}}\)
\(=\left(5\sqrt{3}-\dfrac{3}{2}\cdot\dfrac{1}{\sqrt{3}}-4\sqrt{3}\right)\cdot\dfrac{4}{\sqrt{3}}\)
\(=\sqrt{3}\left(5-\dfrac{1}{2}-4\right)\cdot\dfrac{4}{\sqrt{3}}\)
\(=\left(1-\dfrac{1}{2}\right)\cdot4=2\)
Thực hiện phép tính
A (1+ 2/3 - 1/4) . (0,8 - 3/4)2
b) 16 2/7 : (-3/5) + 28 2/7 : 3/5
Thực hiện phép tính ( tính nhanh nếu có thể)
c) 16 2/7: -3/5 + 28 2/7 : 3/5
d) 3/5 : (-1/15 -1/6) + 3/5 : ( -1/3 - 1 1/15)
Bài 1: Thực hiện các phép tính sau
a, ( x2 -1 )( x2 + 2x )
b, ( x + 3 )( x2 + 3x -5 )
c, ( x -2y )( x2y2 - xy + 2y )
d, ( 1/2xy -1 )( x3 -2x -6 )
a) Ta có: ( x2 -1 )( x2 + 2x )
= x2( x2 + 2x ) - ( x2 + 2x )
= x4 + 2x3 - x2 - 2x
b) Ta có ( x + 3 )( x2 + 3x -5 )
= x( x2 + 3x -5 ) + 3( x2 + 3x -5 )
= x3 + 3x2 - 5x + 3x2 + 9x - 15
= x3 + 6x2 + 4x - 15
c) Ta có ( x -2y )( x2y2 - xy + 2y )
= x( x2y2 - xy + 2y ) - 2y( x2y2 - xy + 2y )
= x3y2 - x2y + 2xy - 2x2y3 + 2xy2 - 4y2
d) Ta có ( 1/2xy -1 )( x3 -2x -6 )
= 1/2xy( x3 -2x -6 ) - ( x3 -2x -6 )
= 1/2x4y - x2y - 3xy - x3 + 2x + 6
Câu 16. Thực hiện phép tính: (3 - x)(3 + x) + (x - 5) ^ 2 . Kết quả bằng: D. 34 - 10x .28 - 10x B. 2x ^ 2 - 10x + 25 A. 34 + 10x
\(\left(3-x\right)\left(3+x\right)+\left(x-5\right)^2\\ =9-x^2+x^2-10x+25\\ =34-10x\)
a)
160 : (4 x 8)
160 : 4 : 8
Thực hiện các phép tính sau
a)96 : (3 x 8)
96 : 3 : 8
105 : (5 x 7)
105 : 5 : 7
b)
270 : (9 x 6)
420 : (7 x 3)
144 : (2 x 8)
a)
160 : (4 × 8) = 160 : 32 = 5
160 : 4 : 8 = 40 : 8 = 5
Vậy 160 : (4 × 8) = 160 : 4 : 8.
96 : (3 × 8) = 96 : 24 = 4
96 : 3 : 8 = 32 : 8 = 4
Vậy 96 : (3 × 8) = 96 : 3 : 8.
105 : (5 × 7) = 105 : 35 = 3
105 : 5 : 7 = 21 : 7 = 3
Vậy 105 : (5 × 7) = 105 : 5 : 7.
Nhận xét: a : (b × c) = a : b : c
b)
270 : (9 × 6) = 270 : 9 : 6 = 30 : 6 = 5
420 : (7 × 3) = 420 : 7 : 3 = 60 : 3 = 20
144 : (2 × 8) = 144 : 2 : 8 = 72 : 8 = 9
Bài 1 : thực hiện phép tính hợp lí
3/5 . 13/46 - 1/10 . 16/23
3/14 : 1/28 - 13/21 : 1/28 + 29/42 : 1/28 - 8
Giúp mình voiw, làm đầy đủ 2 cqau nhé please
1.Thực hiện các phép tính sau :
a) \(-\dfrac{4}{3}.\dfrac{5}{12}+\dfrac{1}{3}.\dfrac{5}{12}\) b)\(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
2.Tìm x, biết:
a) 2x+19=\(^{5^2}\) b)\(-\dfrac{2}{9}x-\dfrac{1}{7}=\dfrac{4}{21}\)
1,
a, \(\left(\dfrac{-4}{3}+\dfrac{1}{3}\right).\dfrac{5}{12}\)=-\(\dfrac{5}{12}\)
b, \(\dfrac{16}{5}+\left(\dfrac{-45}{14}\right):\dfrac{3}{28}\)
=\(\dfrac{-2}{15}\)
2,
a, 2x+19=25
=>x=3
b, \(-\dfrac{2}{9}x=\dfrac{1}{3}\)
=>x=\(\dfrac{-3}{2}\)
Bài 1:
a) Ta có: \(\dfrac{-4}{3}\cdot\dfrac{5}{12}+\dfrac{1}{3}\cdot\dfrac{5}{12}\)
\(=\dfrac{5}{12}\cdot\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)\)
\(=\dfrac{-5}{12}\)
b) Ta có: \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\left(\dfrac{4}{14}-\dfrac{49}{14}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\dfrac{-45}{14}\cdot\dfrac{28}{3}\)
\(=\dfrac{16}{5}-30=\dfrac{-134}{5}\)
1)
a) \(-\dfrac{4}{3}.\dfrac{5}{12}+\dfrac{1}{3}.\dfrac{5}{12}=\dfrac{5}{12}.\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)=\dfrac{5}{12}.\left(-1\right)=-\dfrac{5}{12}\)
b) \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right).\dfrac{28}{3}=3+\dfrac{1}{5}-\dfrac{45}{14}.\dfrac{28}{3}\)
\(=3+\dfrac{1}{5}-30=-27+\dfrac{1}{5}=-\dfrac{134}{5}\)
2)
a) \(2x+19=25\)
\(2x=25-19=6\)
\(x=3\)
b) \(-\dfrac{2}{9}x-\dfrac{1}{7}=\dfrac{4}{21}\)
\(-\dfrac{2x}{9}=\dfrac{4}{21}+\dfrac{1}{7}=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}.\left(-\dfrac{9}{2}\right)=-\dfrac{3}{2}\)
Thực hiện phép tính a) (1/2 - 0,75 ) . ( 0,2 - 2/5) / 5/9 - 1và1/12) b) 2/3 + 2/7-1/14 / - 1 - 3/7 + 3/28
B2 : thực hiện phép tính
a, -3/5 + 9/16 + -2/5 + 7/16
b, 5 2/3 - 1 1/5 - 2 2/3
Helpp
Trả lời :
a)\(-\frac{3}{5}+\frac{9}{16}+-\frac{2}{5}+\frac{7}{16}\)
=\(\left(-\frac{3}{5}+-\frac{2}{5}\right)+\left(\frac{9}{16}+\frac{7}{16}\right)\)
=\(-1+1\)
=\(1\)
b)\(5\frac{2}{3}-1\frac{1}{5}-2\frac{2}{3}\)
=\(\left(5-1-2\right)\left(\frac{2}{3}-\frac{1}{5}-\frac{2}{3}\right)\)
=\(-2\frac{1}{5}\)
Hok_Tốt
#Thiên_Hy
a ) -3/5 + 9/16 + (-2/5 ) + 7/16
[ -3/5 + (-2/5) ] + (9/16 + 7/16 )
-1 + 1
0
b) 5 2/3 - 1 1/5 - 2 2/3
(5 2/3 - 2 2/3) - 1 1/5
3 - 6/1
-3