Bài 3 :
a) \(5\cdot2^2+98:7^2=5\cdot4+98:49=5\cdot4+2=20+2=22\)
b) \(200:\left\{196-\left[187+\left(15+5\right):4\right]:2\right\}\)
\(=200:\left\{196-\left[187+5\right]:2\right\}\)
\(=200:\left(196-96\right)\)
\(=200:100=2\)
Bài 4 :
a) \(4\cdot\left(x-3\right)=7^2-1^3\)
\(4\cdot\left(x-3\right)=48\)
\(x-3=\dfrac{48}{4}\)
\(x-3=12\)
`=>x=12+3=15`
b) \(5x+x=150:2+3\)
\(6x=75+3=78\)
\(x=\dfrac{78}{6}\)
`=>x=13`
B3
a) 5.22+98: 72
=5.4+98:49
=20+2
=22
b) 200:{196-[187+(15+5):4] :2}
= 200:{196-[187+20:4] :2}
= 200:{196-[187+5] :2}
= 200:{196-192 :2}
=200:{196- 96}
=200:100
= 2
B4
a) 4.(x-3)=72-13
4.(x-3)= 49 - 1
4.(x-3)= 48
x-3 = 48 : 4
x-3 = 12
x = 12+3
x = 15
b)5x+x=150:2+3
5x+x=75+3
5x+x= 78
x.(5+1)=78
x. 6= 78
x =78 : 6
x= 13
