c) 93.32+14.16=93.2.16+14.16=16.(186+14)=16.200=3200

e)-8.40+2.108+24=24(9+1)-320=240-320=-80

b)86.15+150.1,4=86.15+15.14=15(86+14)=15.100=1500

d)98,6.199-990.9,86=98,6.199-99.98,6=98,6(199-99)=98,6.100=9860

f)993.98+21.331-50.99,3=993.(98+7-5)=993.100=99300

a) Kết quả -80.                    b) Kết quả 993000.

a) Đặt nhân tử chung là 20,9; thu đuợc 20,9(75 +  5 2 ).

Thực hiện tính nhanh được kết quả 2090.

b) Biến đổi 150.1,4 = 15.10.1,4 = 15.14 đặt nhân tử chung 14.

Sau đó thực hiện tính nhanh được kết quả 1400.

c) Biến đổi 14.16 = 7.2.16 = 7.32, đặt nhân tử chung là 32.

Thực hiện tính nhanh được kết quả là 3200.

d) Biến đổi 990.9,86 = 99.10.9,86 = 99.98,6 đặt nhân tử chung Sau đó thực hiện tính nhanh được kết quả là 9860.

3A:

a: \(75\cdot20.9+5^2\cdot20.9\)

\(=20.9\cdot100\)

=2090

b: \(86\cdot15+150\cdot1.4\)

\(=86\cdot15+15\cdot14\)

\(=15\cdot100=1500\)

c: \(93\cdot32+14\cdot16\)

\(=93\cdot32+32\cdot7\)

=3200

c.93 . 32 + 14 . 16

= 93 . 32 + 7 . 32

= 32 . (93 + 7)

= 32 . 100

= 3200

d.98,6 . 199 - 990 . 9,86

= 98,6 . 199 - 99 . 98,6

= 98,6 . (199 - 99)

= 98,6 . 100

= 9860

HỌC TỐT :D

tính hợp lí

a.75.20,9+

75 . 20,9 + 25

= 20,9 . (75 + 25)

= 20,9 . 100

= 2090

b.86.15+150.1,4

= 86 . 15 + 15 . 14

= 15 . (86 + 14)

= 15 . 100

= 1500

c.93.32+14.16

d.98,6.199-990.9,86

\(\text{∘ Ans}\)

\(\downarrow\)

`1,`

`86.15 + 150. 1,4`

`= 86. 15 + 15. 14`

`= 15.(86 + 14)`

`= 15.100`

`= 1500`

`2,`

`93.32 + 14.16`

`= 93.32 + 2.7.16`

`= 93.32 + 32.7`

`= 32.(93 + 7)`

`= 32.100`

`= 3200`

`3,`

\(98,6\cdot199-990\cdot9,86\)

`=`\(98,6\cdot199-99\cdot98,6\)

`=`\(98,6\cdot\left(199-99\right)\)

`=`\(98,6\cdot100\)

`=`\(9860\)

`4,`

\(85\cdot12,7+5\cdot3\cdot12,7?\)

`=`\(85\cdot12,7+15+12,7\)

`=`\(12,7\cdot\left(85+15\right)\)

`=`\(12,7\cdot100\)

`= 1270`

`5,`

\(0,12\cdot90-110\cdot0,6+36-25\cdot6?\)

\(=6\cdot1,8-11\cdot6+6\cdot6-25\cdot6\)

\(=6\cdot\left(1,8-11+6-25\right)\)

\(=6\cdot\left(-28,2\right)=-169,2\)

a,86.15+150.1,4=(86.15)+(150.1,4)=1290+210=1500

b,93.32+14.16=(93.32)+(14.16)=2976+224=3200

c,98,6.199-990.9,86=(98,6.199)-(990.9,86)=19621,4-9761,4=9860

a) \(86\times15+150\times1,4\)

\(=86\times15+15\times10\times1,4\)

\(=86\times15+15\times14\)

\(=15\times\left(86+14\right)\)

\(=15\times100\)

\(=1500\)

\(a,75\cdot20,9+5^2\cdot20,9=20,9\left(75+25\right)=20,9\cdot100=2090\\ b,86\cdot15+150\cdot1,4=150\left(8,6+1,4\right)=150\cdot10=1500\\ c,93\cdot32+14\cdot16=32\left(93+7\right)=32\cdot100=3200\\ d,98,6\cdot199-990\cdot9,86=98,6\left(199-99\right)=98,6\cdot100=9860\\ e,-8\cdot40+2\cdot108+24=8\left(-40+27+3\right)=8\cdot\left(-10\right)=-80\\ f,993\cdot98+21\cdot331-50\cdot99,3=993\left(98-5+7\right)=993\cdot100=99300\)

\(a,=\left(3-x+1\right)\left(9+3x-3+x^2-2x+1\right)\\ =\left(4-x\right)\left(x^2+x+7\right)\\ b,=4x^2-4xy-13xy+13y^2\\ =4x\left(x-y\right)-13y\left(x-y\right)\\ =\left(4x-13y\right)\left(x-y\right)\\ c,=4\left(x^2-xy-2y^2\right)\\ =4\left(x^2+xy-2xy-2y^2\right)\\ =4\left(x+y\right)\left(x-2y\right)\\ d,=x^3+4x^2+5x^2+20x+6x+24\\ =\left(x+4\right)\left(x^2+5x+6\right)\\ =\left(x+4\right)\left(x^2+2x+3x+6\right)\\ =\left(x+4\right)\left(x+2\right)\left(x+3\right)\\ f,=x\left(x+4y\right)-3\left(x+4y\right)=\left(x-3\right)\left(x+4y\right)\\ g,=4x^3+4x^2-29x^2-29x-24x-24\\ =\left(x+1\right)\left(4x^2-29x-24\right)\\ =\left(x+1\right)\left(4x^2-32x+3x-24\right)\\ =\left(x+1\right)\left(x-8\right)\left(4x+3\right)\)

\(a,27-\left(x-1\right)^3=\left(3-x+1\right)\left[9+3\left(x-1\right)+\left(x+1\right)^2\right]=\left(4-x\right)\left(9+3x-3+x^2+2x+1\right)=\left(4-x\right)\left(x^2+5x+7\right)\)

\(b,4x^2-17xy+13y^2=\left(4x^2-4xy\right)-\left(13xy-13y^2\right)=4x\left(x-y\right)-13y\left(x-y\right)=\left(x-y\right)\left(4x-13y\right)\)

\(c,4x^2-4xy-8y^2=4\left(x^2-xy-2y^2\right)\)

\(d,x^3+9x^2+26x+24=\left(x^3+2x^2\right)+\left(7x^2+14x\right)+\left(12x+24\right)=\left(x+2\right)\left(x^2+7x+12\right)=\left(x+2\right)\left[\left(x^2+3x\right)+\left(4x+12\right)\right]=\left(x+2\right)\left(x+3\right)\left(x+4\right)\)

\(f,4xy+x^2-3x-12y=x\left(4y+x\right)-3\left(x+4y\right)=\left(x+4y\right)\left(x-3\right)\)

\(g,4x^3-25x^2-53x-24=\left(4x^3-32x^2\right)+\left(7x^2-56x\right)+\left(3x-24\right)=\left(4x^2+7x+3\right)\left(x-8\right)=\left[\left(4x^2+4x\right)+\left(3x+3\right)\right]=\left(4x+3\right)\left(x+1\right)\left(x-8\right)\)