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\(\left(19x+2.5^1\right):14=\left(13-8\right)^2-4^2.\)
\(\left(19x+10\right):14=5^2-4^2\)
\(\left(19x:4\right)+\left(10:4\right)=25-16\)
\(\left(19x:4\right)+\frac{5}{2}=9\)
\(19x:4=9-\frac{5}{2}\)
\(19x:4=\frac{13}{2}\)
\(19x=\frac{13}{2}.4=26\)
\(x=\frac{26}{19}\)
a) \(\left(19x+2\cdot5^2\right):14=\left(13-8\right)^2-4^2\)
\(\Leftrightarrow\left(19x+2\cdot25\right):14=5^2-4^2\)
\(\Leftrightarrow19x+50=\left(25-16\right)\cdot14\)
\(\Leftrightarrow19x+50=9\cdot14\)
\(\Leftrightarrow19x+50=126-50\)
\(\Leftrightarrow19x=76\)
\(\Leftrightarrow x=76:19\)
\(\Leftrightarrow x=4\)
b) \(x+\left(x+1\right)+\left(x+2\right)+...+\left(x+30\right)=1240\)
\(\Leftrightarrow\left(x+x+x+x...+x\right)+\left(1+2+3+...+30\right)=1240\)
\(\Leftrightarrow31x+\frac{\left[\left(30-1\right):1+1\right]\cdot\left(30+1\right)}{2}=1240\)
\(\Leftrightarrow31x+465=1240\)
\(\Leftrightarrow31x=775\)
\(\Leftrightarrow x=25\)
c)\(11-\left(-53+x\right)=97\)
\(\Leftrightarrow-53+x=-86\)
\(\Leftrightarrow x=-33\)
d) \(-\left(x+84\right)+213=-16\)
\(\Leftrightarrow-\left(x+84\right)=-229\)
\(\Leftrightarrow x+84=229\)
\(\Leftrightarrow x=145\)
=(-64).159+34.4.(-16)+(-123).(-64)
=(-64).159+34.(-64)+(-123).(-64)
=(-64).(159+34-123)
(-64).70
=-4480
Giải:
\(1+\left(x-\frac{2}{3}\right)^2=\frac{37}{64}\Rightarrow\left(x-\frac{2}{3}\right)^2=-\frac{27}{64}\)
\(\Leftrightarrow x-\frac{2}{3}=-\sqrt{\frac{27}{64}}\Leftrightarrow x=-\sqrt{\frac{27}{64}}+\frac{2}{3}\)
Vậy \(x=\sqrt{\frac{27}{64}}-\frac{2}{3}\)
\(a,\left(19x+2.5^2\right):14=\left(13-8\right)^2-4^2\)
\(\Leftrightarrow\left(19x+50\right):14=5^2-4^2\)
\(\Leftrightarrow\left(19x+50\right):14=9\)
\(\Leftrightarrow19x+50=126\)
\(\Leftrightarrow19x=76\Leftrightarrow x=4\)
b) x + ( x + 1 ) + ( x + 2 ) + ... + ( x + 30 ) = 1240
x + x + 1 + x + 2 + ... + x + 30 = 1240
( x + x + ... + x ) + ( 1 + 2 + ... + 30 ) = 1240
Số số hạng là : ( 30 - 1 ) : 1 + 1 = 30 ( số )
Tổng là : ( 30 + 1 ) . 30 : 2 = 465
=> 31x + 465 = 1240
=> 31x = 775
=> x = 25
Vậy........
( − 37 ) .84 + 37. ( − 16 ) = ( − 37 ) .84 + ( − 37 ) .16 = ( − 37 ) . ( 84 + 16 ) = ( − 37 ) .100 = − 3700
Tính bằng cách hợp lý nhất:
\(a)\)\(-64.159+136.\left(-8\right)^2+123.64\)
\(=64.\left(-159\right)+136.64+123.64\)
\(=64.\left(-159+123+136\right)\)
\(=64.100\)
\(=6400\)
\(b)\)\(84.\left(16-37\right)-16.\left(37+84\right)\)
\(=84.16-84.37-16.37-16.84\)
\(=84.\left(16-16\right)-37.\left(84+16\right)\)
\(=84.0-37.100\)
\(=0-3700\)
\(=-3700\)