Đáp án:
Giải thích các bước giải:
Bài 4:
a)
$30240:x=42$
$x=30240:42$
$x=720$
b)
$x\,\,\,\text{x}\,\,\,12=2412$
$x\,\,\,\,\,\,\,\,\,\,\,\,\,\,=2412:12$
$x\,\,\,\,\,\,\,\,\,\,\,\,\,\,=201$
c)
$x\,\,\,\text{x}\,\,\,37=1135$
$x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=1135:37$
$x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=\dfrac{1135}{37}$
d)
$25\,\,\,\text{x}\,\,\,x=9100$
$x=9100:25$
$x=364$
e)
$\left( x+3 \right)\,\text{x}\,247=40755$
$x+3\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=40755:247$
$x+3\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=165$
$x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=165-3$
$x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=162$
f)
$57316:\left( x-8 \right)=623$
$x-8=57316:623$
$x-8=92$
$x\,\,\,\,\,\,\,\,=92+8$
$x\,\,\,\,\,\,\,\,=100$
Bài 5:
a) $2\,{{\text{m}}^{2}}=200\,\text{d}{{\text{m}}^{2}}$
b) $1\,{{\text{m}}^{2}}=10\,\,000\,\text{c}{{\text{m}}^{2}}$
c) $1\,\text{k}{{\text{m}}^{2}}=1\,\,000\,\,000\,{{\text{m}}^{2}}$
d) $36\,\text{d}{{\text{m}}^{2}}=3600\,\text{c}{{\text{m}}^{2}}$
e) $508\,\text{d}{{\text{m}}^{2}}=50800\,\text{c}{{\text{m}}^{2}}$
g) $3100\,\text{c}{{\text{m}}^{2}}=21\,\text{d}{{\text{m}}^{2}}$
h) $2007\text{c}{{\text{m}}^{2}}=20\,\text{d}{{\text{m}}^{2}}7\,\text{c}{{\text{m}}^{2}}$
k) $6\,\text{d}{{\text{m}}^{2}}=600\,\text{c}{{\text{m}}^{2}}$
