Bài 3 : áp dụng các tính chất của phép cộng và phép nhân , tính nhanh :
a) (1989 x 1990 + 3978 ) : ( 1992 x 1991 - 3984 )
b ) ( 637 x 527 - 189 ) : ( 526 x 637 + 448 )
Giúp mình với ạ ! Mình đang cần gấp
Tính hợp lí :
a= 39 x 118 +29 x 82
b = 37 x 39 + 78 x 14 + 13 x 85 + 52 x 55
c= 368 : 16 + 752 : 16 + 480 : 16
d= 5 x 11 x 18 + 9 x 31 x 10 + 4 x 29 x 45
a) \(39\times118+29\times82\)
\(=39\times2\times59+29\times2\times41\)
\(=2\times\left(39\times59+29\times41\right)\)
\(=2\times\left(2301+1189\right)\)
\(=2\times3490\)
\(=6980\)
b) \(37\times39+78\times14-13\times85-52\times55\)
\(=37\times3\times13+6\times13\times14+13\times85-4\times13\times55\)
\(=13\times\left(37\times3+6\times14+85-4\times55\right)\)
\(=13\times\left(111+84+85-220\right)\)
\(=13\times\left(280-220\right)\)
\(=13\times60\)
\(=780\)
c) \(368:16+752:16+480:16\)
\(=\left(368+752+480\right):16\)
\(=\left(1120+480\right):16\)
\(=1600:16\)
\(=100\)
d) \(5\times11\times18+9\times31\times10+4\times29\times45\)
\(=5\times11\times9\times2+9\times31\times10+2\times2\times29\times5\times9\)
\(=10\times9\times11+10\times9\times31+10\times29\times2\times9\)
\(=90\times11+90\times31+90\times29\times2\)
\(=90\times\left(11+31+29\times2\right)\)
\(=90\times\left(42+58\right)\)
\(=90\times100\)
\(=9000\)
Tính nhanh:
a)1996 x 1995 - 996/1000 + 1996 x 1994
b) 637 x 527 - 189/526 x 637 + 448
c)677 x 874 + 251/678 x 874 - 623
d) 15 x 2121/4343 + 15 x 222222/434343
e) 16 x 25 + 44 x100/29 x 96 + 142 x 48
g) 1994 x 1993 - 1992 x 1993/1992 x 1993 + 1994 x 7 + 1986
Các bạn giúp mình nha !
(637 x 527-189) : (526 x 637 +448)
\(\dfrac{637\times527-189}{526\times637+448}\)
\(=\dfrac{637\times\left(526+1\right)-189}{526\times637+448}\)
\(=\dfrac{637\times526+637-189}{526\times637+448}\)
\(=\dfrac{637\times526+448}{526\times637+448}\)
\(=\dfrac{1}{1}\)
\(=1\)
\(\dfrac{\left(637\cdot527-189\right)}{\left(526\cdot637+448\right)}\)
\(=\dfrac{\left(637\cdot526+637-189\right)}{\left(526\cdot637+448\right)}\)
\(=\dfrac{637\cdot526+448}{637\cdot526+448}=1\)
Bài 2 tính nhanh a,15 x 2121/4343 + 15 x 222222/434343 b,399 x 45 + 55 x 399/1995 x 1996 - 1991 x 1995 c,1996 x 1995 - 996/1000 + 1996 x 1994 d,637 x 527 - 189/526 x 637 + 448 e,677 x 874 + 251/678 x 874 - 623 khẩn cấp huhuhu.......... aaaaaaaaaa
a, 15(21/43+22/43)=15.1=15
b, 399(45+55) / 1995(1996-1991)
=399.100 / 1995.5
=4
tính nhanh :
c) 637 x 527 - 189 / 526 x 637 + 448
d) 677 x 874 + 251 / 678 x 874 - 623
\(\frac{637\times527-189}{526\times637+448}\)
\(=\frac{637\times\left(526+1\right)-189}{526\times637+448}\)
\(=\frac{637\times526+637-189}{526\times637+448}\)
\(=\frac{637\times526+448}{526\times637+448}\)
\(=1\)
\(\frac{677\times874+251}{678\times874-623}\)
\(=\frac{677\times874+251}{\left(677+1\right)\times874-623}\)
\(=\frac{677\times874+251}{677\times874+874-623}\)
\(=\frac{677\times874+251}{677\times874+251}\)
\(=1\)
\(\frac{637\times527-189}{526\times637+448}\)
\(=\frac{526\times637+637-189}{526\times637+448}=\frac{526\times637+448}{526\times637+448}=1\)
tính nhanh :
c) 637 x 527 - 189 / 526 x 637 + 448
d) 677 x 874 + 251 / 678 x 874 - 623
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
tính nhanh :
c) 637 x 527 - 189 / 526 x 637 + 448
d) 677 x 874 + 251 / 678 x 874 - 623
c) 637 x 527 - 189=335510 / 526 x 637 + 448=335510
d) 677 x 874 + 251 =591949 / 678 x 874 - 623=591949
học tốt
c, 637x527-189/526x637+448=335918,116
d, 677x874+251/678x874-623=91398,5605
\(\frac{677\times874+251}{678\times874-623}\)
\(=\frac{677\times874+251}{677\times874+874-623}=\frac{677\times874+251}{677\times874+251}\)
\(=1\)
tính nhanh :
c) 637 x 527 - 189 / 526 x 637 + 448
d) 677 x 874 + 251 / 678 x 874 - 623
saaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadaaaaaaaaaaaaaaaaaaaaaaaaaaaaaoaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
\(\frac{637x527-189}{526x637+448}\)
\(=\frac{527-189}{526+448}\)
\(=\frac{526-188}{526+448}\)
\(=\frac{188}{448}=\frac{47}{112}\)
