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= 0,8 x 96 + 0,8 x 2 x2
= 0,8 x 96 +0,8 x 4
= 0,8 ( 96 + 4 )
= 0,8 x 100
= 80
a) \(\left(45x105-225\right)-\left(210+42x95\right)\)
\(=45x\left(100+5\right)-225-210+42x\left(100-5\right)\)
\(=4500+45x5-225-210+4200-42x5\)
\(=4500+4200+45x5-42x5-225-210\)
\(=8700+5x\left(45-42\right)-435\)
\(=8700+15-435=8280\)
a: =45*105-225-210-42*95
=45*(105-5)-42(95+5)
=100*3
=300
b: =47(105-5)-42(96+4)
=47*100-42*100
=5*100
=500
`@` `\text {Ans}`
`\downarrow`
`a)`
`13/50 + 9% + 41/100 + 0,24`
`= 0,26 + 0,09 + 0,41 + 0,24`
`= (0,26 + 0,24) + (0,09 + 0,41)`
`= 0,5 + 0,5`
`= 1`
`b)`
`2018 \times 2020 - 1/2017 + 2018 \times 2019`
`= 2018 \times (2020 + 2019) - 1/2017`
`= 2018 \times 4039 - 1/2017`
`= 8150702`
`c)`
`1/2 + 1/6 + 1/12 + 1/20 +1/30 +1/42`
`=`\(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}\)
`=`\(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{6}-\dfrac{1}{7}\)
`=`\(1-\dfrac{1}{7}\)
`= 6/7`
\(a,\dfrac{13}{50}+9\%+\dfrac{41}{100}+0,24\\ 0,26+0,09+0,41+0,24\\ =\left(0,26+0,24\right)+\left(0,09+0,41\right)\\ =0,5+0,5\\ =1\\ b,2018\times2020-\dfrac{1}{2017}+2018\times2019\\ =2018\times\left(2020+2019\right)-\dfrac{1}{2017}\\ =2018\times4039-\dfrac{1}{2017}\\ =3150702-\dfrac{1}{2017}\\ c,\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}\\ =1-\dfrac{1}{2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}\\ =1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}.........+\dfrac{1}{6}-\dfrac{1}{7}\\ =1-\dfrac{1}{7}\\ =\dfrac{6}{7}\)
a)=4,86x10
=48,6
b)=10x6,94
=69,4
c)=72,9x99+72,9
=72,9x(99+1)
=72,9x100
=7290
d)=0,8x96+0,8x2x2
=0,8x(96+2x2)
=0,8x100
=80
a, = 4,86 x (0,25 x 40) = 4,86 x 10 = 48,6
b, = (0,125 x 80) x 6,94 = 10 x 6,94 = 69,4
k mk nha
\(a.0,4:x=1,6-0,5:x.\\ 0,4:x+0,5:x=1,6.\\ \left(0,4+0,5\right):x=1,6.\\ 0,9:x=1,6.\\ x=\dfrac{9}{16}.\)
\(b.72,6-x\times25=68,6.\\ x\times25=4.\\ x=\dfrac{4}{25}.\)
72,9 x 99 + 72 + 0,9 = 72,9 x 99 + 72,9 = 72,9 x (99 + 1) = 72,9 x 100 = 7290
0,8 x 96 + 1,6 x 2 = 0,8 x 96 + 0,8 x 2 x 2 = 0,8 x 96 + 0,8 x 4 = 0,8 x (96 + 4) = 0,8 x 100 = 80
`#3107.101107`
`a)`
`4,57 \times 42 + 5,43 \times 42`
`= 42 \times (4,57 + 5,43)`
`= 42 \times 10`
`= 420`
`b)`
`8,4 \times 96 + 1,6 \times 96`
`= 96 \times (8,4 + 1,6)`
`= 96 \times 10`
`= 960`
a) 4,57x42+5,43x42
= (4,57+5,43)x42
= 10x42
=420
b) 8,4x96+1,6x96
= (8,4+1,6)x96
= 10x96
= 960