Câu hỏi của Min Yoongi 민윤기

Question

câu 1:Tính nhanh

a)(-25).21.(-2)2.(-|-3|).(-1)2n+1(n∈N*)

b)(-5)3.67.(-|-23|).(-1)2n(n∈N*)

c)35.18-5.7.28

d)24.(16-5)-16.(24-5)

e)29.(19-13)-19.(19.-13)

g)31.(-18)+31.(-81).31

h)(-12).47+(-12).5...

Nguyễn Lê Phước Thịnh · Accepted Answer

Câu 1:

a) Ta có: 2n+1 là số lẻ∀n

⇒$\left(-1\right)^{2n+1}=-1$

Ta có: $\left(-25\right)\cdot21\cdot\left(-2\right)^2\cdot\left(-\left|-3\right|\right)\cdot\left(-1\right)^{2n+1}$

$=-25\cdot21\cdot4\cdot\left(-3\right)\cdot\left(-1\right)$

$=75\cdot84\cdot\left(-1\right)$

$=-6300$

b) Ta có: $\left(-5\right)^3\cdot67\cdot\left(-\left|-2^3\right|\right)\cdot\left(-1\right)^{2n}$

$=-125\cdot67\cdot\left(-8\right)$

$=1000\cdot67=67000$

c) Ta có: $35\cdot18-5\cdot7\cdot28$

$=35\cdot18-35\cdot28$

$=35\cdot\left(18-28\right)=35\cdot\left(-10\right)=-350$

d) Ta có: $24\cdot\left(16-5\right)-16\cdot\left(24-5\right)$

$=24\cdot16-24\cdot5-24\cdot16+16\cdot5$

$=-24\cdot5+16\cdot5$

$=5\cdot\left(-24+16\right)=5\cdot\left(-8\right)=-40$

e) Ta có: $29\cdot\left(19-13\right)-19\cdot\left(19-13\right)$

$=6\cdot\left(29-19\right)=6\cdot10=60$

g)Sửa đề: $31\cdot\left(-18\right)+31\cdot\left(-81\right)-31$

Ta có: $31\cdot\left(-18\right)+31\cdot\left(-81\right)-31$

$=31\cdot\left(-18-81-1\right)$

$=31\cdot\left(-100\right)=-3100$

h) Ta có: $\left(-12\right)\cdot47+\left(-12\right)\cdot52+\left(-12\right)$

$=-12\cdot\left(47+52+1\right)$

$=-12\cdot100=-1200$

k) Ta có: $13\cdot\left(23+22\right)-3\cdot\left(17+28\right)$

$=13\cdot45-3\cdot45$

$=45\cdot\left(13-3\right)=45\cdot10=450$

m) Ta có: $-48+48\cdot\left(-78\right)+48\cdot\left(-21\right)$

$=48\cdot\left(-1-78-21\right)$

$=48\cdot\left(-100\right)=-4800$

n) Ta có: $135\cdot\left(171-123\right)-171\cdot\left(135-123\right)$

$=135\cdot171-135\cdot123-171\cdot135+171\cdot123$

$=123\cdot\left(-135+171\right)=123\cdot36=4428$Câu trả lời: Câu 1: