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\(\dfrac{637\times527-189}{526\times637+448}\)
\(=\dfrac{637\times\left(526+1\right)-189}{526\times637+448}\)
\(=\dfrac{637\times526+637-189}{526\times637+448}\)
\(=\dfrac{637\times526+448}{526\times637+448}\)
\(=\dfrac{1}{1}\)
\(=1\)
\(=\dfrac{637.\left(526+1\right)-189}{526.637+448}=\dfrac{637.526+637-189}{526.637+446}=\dfrac{637.526+448}{526.637+448}=1\)
\(\left(637.527-189\right):\left(526.637+448\right)\)
\(=\left(335699-189\right):\left(335062+448\right)\)
\(=335510:335510\)
\(=1\)
Bạn tham khảo lời giải:
a) (1 989. 1 990 + 3 978): (1 992. 1 991 – 3 984)
+) 1 989. 1 990 + 3 978 = 1 989. 1 990 + 1 989. 2 = 1 989. (1 990 + 2) = 1 989. 1 992
+) 1 992. 1 991 – 3 984 = 1 992. 1 991 – 1 992. 2 = 1 992. (1 991 – 2) = 1 992. 1 989
Do đó:
(1 989. 1 990 + 3 978): (1 992. 1 991 – 3 984)
= (1 989. 1 992): (1 992. 1 989)
= (1 989: 1 989). (1 992: 1 992)
= 1. 1
= 1
b) (637. 527 – 189): (526. 637 + 448)
+) 637. 527 – 189 = 637. (526 + 1) – 189 = 637. 526 + 637. 1 – 189
= 637. 526 + (637 – 189) = 637. 526 + 448
Do đó: (637. 527 – 189): (526. 637 + 448) = (637. 526 + 448): (637. 526 + 448) = 1.
\(a)\)\(\left(1989.1990+3978\right)\div\left(1992.1991-3984\right)\)
\(=\)\(\left(1989.1990+1989.2\right)\div\left(1992.1991-1992.2\right)\)
\(=\)\(\left[1989.\left(1990+2\right)\right]\div\left[1992.\left(1991-2\right)\right]\)
\(=\)\(\left(1989.1991\right)\div\left(1992.1989\right)\)
\(=\)\(1\)
\(b)\)\(\left(637.527-189\right)\div\left(526.637+448\right)\)
\(=\)\(\left[637.\left(526-1\right)-189\right]\div\left(526.637-448\right)\)
\(=\)\(\left[637.526+\left(637-198\right)\right]\div\left(637.526-448\right)\)
\(=\)\(\left(636.526+448\right)\div\left(637.526-448\right)\)
\(=\)\(1\)
a ) 17 x 4 = ( 15 + 2 ) x 4 = 15 x 4 + 2 x 4 = 60 + 8 = 68
25 x 28 = 25 x ( 20 + 8 ) = 25 x 20 + 25 x 8 = 500 + 200 = 700
b ) 13 x 12 = 13 x ( 10 + 2 ) = 13 x 10 + 13 x 2 = 130 + 26 = 156
53 x 11 = 53 x ( 10 + 1 ) = 53 x 10 + 53 x 1 = 530 + 53 = 583
39 x 101 = 39 x ( 100 + 1 ) = 39 x 100 + 39 x 1 = 3900 + 39 = 3939
a) Ta có:
\(17\times4=\left(15+2\right)\times4=15\times4+2\times4=60+8=68\)
\(25\times28=25\times\left(20+8\right)=25\times20+25\times8=500+200=700\)
b) Ta có:
\(13\times12=13\times\left(10+2\right)=13\times10+13\times2=130+26=156\)
\(53\times11=53\times\left(10+1\right)=53\times10+53\times1=530+53=583\)
\(39\times101=39\times\left(100+1\right)=39\times100+39\times1=3900+39=3939\)
Lời giải:
a. $=128-78+100-128=(128-128)+100-78=0+100-78=22$
b. $=125-100+93-218= (125+93-218)-100=0-100=-100$
c. $=453+74-79-527$
$=(453+74-527)-79 =0-79=-79$
d.
$=-825+775+825=(825-825)+775=0+775=775$
e.
$=163-413-187+637 = (163+637)-(413+187) = 800-600=200$
