Bài 1: Tính giá trị biểu thức
a) 1574,8 : 25,4 + 72 × 0,5
b) 375,42+ 95,8 × 0,1 - 207,6 nhanh chi tiết ạ !
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Bài 2:
a: \(2m^2=200dm^2\)
b: \(1m^2=10000cm^2\)
c: \(1km^2=1000000m^2\)
d: \(36dm^2=3600cm^2\)
e: \(508dm^2=50800cm^2\)
f: \(3100cm^2=31dm^2\)
2:
a: \(=\dfrac{1}{3}\left(-\dfrac{4}{5}-\dfrac{6}{5}\right)=-\dfrac{1}{3}\cdot2=-\dfrac{2}{3}\)
1:
\(A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)
\(=-4-\dfrac{1}{4}=-\dfrac{17}{4}\)
Bài 1:
\(A=\left(7-\dfrac{3}{4}+\dfrac{1}{3}\right)-\left(6+\dfrac{5}{4}-\dfrac{4}{3}\right)-\left(5-\dfrac{7}{4}+\dfrac{5}{3}\right)\)
\(A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)
\(A=\left(7-6-5\right)-\left(\dfrac{3}{4}+\dfrac{5}{4}-\dfrac{7}{4}\right)+\left(\dfrac{1}{3}+\dfrac{4}{3}-\dfrac{5}{3}\right)\)
\(A=-4-\dfrac{3+5-7}{4}+\dfrac{1+4-5}{3}\)
\(A=-4-\dfrac{1}{4}+\dfrac{0}{3}\)
\(A=-\dfrac{16}{4}-\dfrac{1}{4}+0\)
\(A=\dfrac{-16-1}{4}\)
\(A=-\dfrac{17}{4}\)
Bài 2:
\(\dfrac{1}{3}\cdot-\dfrac{4}{5}+\dfrac{1}{3}\cdot-\dfrac{6}{5}\)
\(=\dfrac{1}{3}\cdot\left(-\dfrac{4}{5}-\dfrac{6}{5}\right)\)
\(=\dfrac{1}{3}\cdot\dfrac{-4-6}{5}\)
\(=\dfrac{1}{3}\cdot\dfrac{-10}{5}\)
\(=\dfrac{1}{3}\cdot-2\)
\(=-\dfrac{2}{3}\)
Ta có: \(A=\left(x-3\right)^2+\left(11-x\right)^2\)
\(=x^2-6x+9+x^2-22x+121\)
\(=2x^2-28x+130\)
\(=2\left(x^2-14x+49+16\right)\)
\(=2\left(x-7\right)^2+32\ge32\forall x\)
Dấu '=' xảy ra khi x=7
A=x(y+2)+2(y+2)=(x+2)(y+2)=100.100=10000
B=9\(^2\)(9+1) +11(-9-1)=\(9^2\).10+11.(-10)=810-110=700
a)[(-15).8]:4
=-120:4
=30
b)[(-125):(-5)].(-13)
=25.(-13)
=325
a,=62+36
=98
b,=375,42+9,58-207,6
=385-207,6
=177,4
a)=(1574,8:25,4)+72x0,5
=62+36
=98
b)=(375,42-207,6)+(95,8x0,1)
=167,82+9,58
=177,4