a) 5/(-4) . 16/25 + (-5)/4 . 9/25
b) 38/45 – ( 8/45 – 17/51 – 3/11)
b2
a) (14/5 . x – 50) : 2/3 = 51
b) ( 3/5 -x) ³ = -64
c) (2x -1) . ( (-1/3 x + 4) =0
a) 5/(-4) . 16/25 + (-5)/4 . 9/25 b) 38/45 – ( 8/45 – 17/51 – 3/11) b2 a) (14/5 . x – 50) : 2/3 = 51 b) ( 3/5 -x) ³ = -64 c) (2x -1) . ( (-1/3 x + 4)
By Kaylee
Đáp án:
Giải thích các bước giải:
a,5/(-4) . 16/25 + (-5)/4 . 9/25
=5/(-4).(4/5)²+(-5)/4.(3/5)²
=-4/5+(-9/20)
=-5/4
b, 38/45 – ( 8/45 – 17/51 – 3/11)
= 38/45-8/45+17/51+3/11
=2/3+20/33
=14/11
bài 2
a, (14/5 . x – 50) : 2/3 = 51
⇔(14/5 . x – 50)=51.2/3
⇔14/5 . x – 50=34
⇔14/5 . x=84
⇔x=84:14/5
⇔x=30
vậy x=30
b, ( 3/5 -x) ³ = -64
⇔( 3/5 -x) ³=(-4)³
⇔3/5-x=-4
⇔x=3/5+4
⇔x=23/5
c, (2x -1) . ( (-1)/3 x + 4) =0
TH1:
2x-1=0
⇔2x=1
⇔x=1/2
TH2:
(-1)/3 x + 4 =0
⇔ (-1)/3 x=-4
⇔x=-4:(-1/3)
⇔x=12
vậy x∈{1/2;12)
CHÚC BẠN HOK TỐT:)))
1)
a)5/(-4) . 16/25 + (-5)/4 . 9/25
=-5/4×(16/25+9/25)
=-5/4×25/25=-5/4×1=-5/4
b)38/45 – ( 8/45 – 17/51 – 3/11)
=30/45+17/51+3/11=2/3+17/51+3/11
=34/51+17/51+3/11
=51/51+3/11=1+3/11=14/11
2)(14/5×x-50)÷2/3=51
⇒14/5×x-50=34
⇒14/5×x=84
⇒x=30
b)(3/5 -x) ³ = -64
⇒3/5-x=-4
⇒x=3/5+4=23/5
c)(2x -1) . (-1/3 x + 4) =0
⇒2x-1=0 hoặc -1/3×x+4=0
⇒x=1/2 hoặc x=12
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