giúp mình với
Tính nhanh:
a, (-38)x47+(-38)x52+(-38)
b,29x(-35)+(-29)x64+(-29)
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a: =38/57x40/50=2/3x4/5=8/15
b: =35/32(27/20+5/20)=35/32x32/20=35/20=7/4
a) 29 + 132 + 237 + 868 + 763
= ( 132 + 868 ) + ( 237 + 763 ) + 29
= 1000 + 1000 + 29
= 1000 x 2 + 29
= 2000 + 29
= 2029
b) 35 x 34 + 35 x 38 + 65 x 75 + 45
= 35 x ( 34 + 38 ) + 65 x 75 + 45
= 35 x 72 + 65 x 75 + 45
= 2520 + 4875 + 45
= 2520 + 4920
= 7440
c) 3 x 25 x 8 + 4 x 37 x 6 + 2 x 38 x 12
= ( 3 x 8 ) x 25 + ( 4 x 6 ) x 37 + ( 2 x 12 ) x 38
= 24 x 25 + 24 x 37 + 24 x 38
= 24 x ( 25 + 37 + 38 )
= 24 x 100
= 2400
a)29+132+237+868+763
=(132+868)+(237+763)+29
= 1000 + 1000 +29
= 2029
a, \(\dfrac{90}{37}-\dfrac{38}{25}-\dfrac{8}{25}-\dfrac{4}{25}\)
= \(\dfrac{90}{37}\) - \(\dfrac{38+8+4}{25}\)
= \(\dfrac{90}{37}\) - 2
= \(\dfrac{16}{37}\)
\(\dfrac{24}{29}\) + \(\dfrac{32}{41}\) + \(\dfrac{34}{29}\) + \(\dfrac{50}{41}\)
=(\(\dfrac{24}{29}\) + \(\dfrac{34}{29}\)) + (\(\dfrac{32}{41}\) + \(\dfrac{50}{41}\))
= \(\dfrac{58}{29}\) + \(\dfrac{82}{41}\)
= 2 + 2
= 4
Bài 1:
a) −x + 8 = −17
−x = −17 − 8
−x = −25
⇒ x = 25
Vậy x = 25
b) 35 − x = 37
x = 35 − 37
x = −2
Vậy x = −2
c) x − 45 = −17
x = −17 + 45
x = 28
Vậy x = 28
d) |x + 1| = 20 (>0)
TH1: x + 1 = 20 TH2: x + 1 = −20
x = 20 − 1 x = −20 − 1
x = 19 x = −21
Vậy x∈\(\left\{-21;19\right\}\)
e) |x − 3| − 16 = −4
|x − 3| = −4 + 16
|x − 3| = 12 (>0)
TH1: x − 3 = 12 TH2: x − 3 = −12
x = 12+3 x = −12 + 3
x = 15 x = −9
Vậy x∈\(\left\{-9;15\right\}\)
Lời giải:
$\frac{24}{19}+\frac{7}{38}+\frac{31}{38}+\frac{5}{38}$
$=\frac{48}{38}+\frac{7}{38}+\frac{31}{38}+\frac{5}{38}$
$=\frac{48+7+31+5}{38}=\frac{91}{38}$
a) x-(12-25)=-8
<=> x+13=-8
<=> x=-21
b) (x-29)-(17-38)=-9
<=> x-29+21=-9
<=> x-8=-9
<=> x=-1
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23.\(\sqrt{14-2\sqrt{33}}=\sqrt{\left(\sqrt{11}\right)^2-2.\sqrt{11}.\sqrt{3}+\left(\sqrt{3}\right)^2}\)
\(=\sqrt{\left(\sqrt{11}-\sqrt{3}\right)^2}=\left|\sqrt{11}-\sqrt{3}\right|=\sqrt{11}-\sqrt{3}\)
28. \(\sqrt{25-4\sqrt{6}}=\sqrt{\left(2\sqrt{6}\right)^2-2.2\sqrt{6}.1+1^2}=\sqrt{\left(2\sqrt{6}-1\right)^2}\)
\(=\left|2\sqrt{6}-1\right|=2\sqrt{6}-1\)
29.\(\sqrt{14-8\sqrt{3}}=\sqrt{14-2\sqrt{48}}=\sqrt{\left(\sqrt{8}\right)^2-2\sqrt{6}.\sqrt{8}+\left(\sqrt{6}\right)^2}\)
\(=\sqrt{\left(\sqrt{8}-\sqrt{6}\right)^2}=\left|\sqrt{8}-\sqrt{6}\right|=\sqrt{8}-\sqrt{6}\)