1/ Tinh nhanh : 72 + 36 x 2 +18 x 2 x 6
Tính nhanh:
Câu 1: 36 x 42 + 2 x 17 x 18 + 9 x 41 x 6
Câu 2: 28 x 47 + 28 x 43 + 72 x 29 + 72 x 61
tinh nhanh 72 x 19 + 36 x 6 x 10 + 144 x 40 - 72 x 29
`= 72 xx 19 + 36 xx 2 xx3 xx 10 + 72 xx 80 - 72 xx 29`
`= 72 xx(19 + 30 - 29 + 80)`
`= 72 xx 100`
`= 7200`
\(=72.19+36.2.3.10+72.2.40-72.29\)
\(=72.19+72.30+72.80-72.29\)
\(=72.\left(19+30+80-29\right)\)
\(=72.100=7200\)
1)x-72:36=18 2)x/3-1/4=-5/6
1, x-72:36=18
x-2=18
=> x=20
2, \(\dfrac{x}{3}-\dfrac{1}{4}=\dfrac{-5}{6}\)
\(\dfrac{x}{3}=\dfrac{-7}{12}\)
12x= -21
->x= \(\dfrac{-21}{12}\)
x/3-1/4=-5/6
x/3=-5/6+1/4
x/3=-7/12
x=-7/12.3
x=-7/4
tinh nhanh
{1+2+3+...............+49+50}x{18:2-72:8}
{1+2+3+...............+49+50} x {18:2-72:8}
={1+2+3+...............+49+50} x {9 - 9}
={1+2+3+...............+49+50} x 0
= 0
18 : 2 - 72 : 8 = 9 - 9 = 0
=> tích = 0
= ( 1 + 49 ) + ( 2 + 48 ) + ( 3 + 47 ) ... cứ như vậy ta được 24 cặp.
= 50 x 24 + 25
= 1225 x ( 18 : 2 - 72 : 8 )
= 1225 x 0
= 0
ko ai muốn kb đâu hehe
72 x 36 x 2 + 24 x 3 + 18 x 4 + 12 x 6 + 144
tinh nhanh
e) 64 x 6 + 82 x 4 + 18 x 6
f) 72 x 54 + 144 x 23
1tính
a) (-6-18 ) : (-4)
b) -28 . (50-42 ) - 35 . ( 34 - 62 )
c) -18 - (-5) + 26
d) -72 . 69 + 31 . (-72)
e) 7 . (-6)2 + ( -42) .17
f) (-38+45 ). ( -36)
2 tìm x
a) x + 49 = 17
b) 18-3x=-15
c) (x-5)=2
d) 15-3(x-2)=-6
e) 36-(18+x)=55
f) -4 |x|=-12
a)(-6-18):(-4)
= { (-6) + (-8) } : (-4)
=(-24) : (-4)= (-6)
b)-28.(50-42)-35.(34-62)
= -28.8-35.(-28)
= -28.(8-35)
= -28.(-27)=756
c)-18-(-5)+26
= -18+5+26
= -13+26=13
d)-72.69+31.(-72)
= -72.(69+31)
= -72.100=-7200
72 + 36 x 2 + 24 x 3 + 18 x 4 + 12 x 6 + 168 / 2 + 2 + 4 + 6 + 10 + ...+ 68