a)37*(64+36)=37*100=3700

b)35*(34+86)+65*(75+45)=35*120+65*120=120*(35+65)=120*100=12000

c) 32*25=8*4*5*5=8*5*4*5=40*20=800

d)57*99=57*(100-1)=5700-57=5643

e)44*102=44*(100+2)=4400+88=4488

f) 12+120/(2.25+10)=12+120/60=12+2=14

a) 35*(34+86)+65*(75+45)=35*120+65*120=120*(35+65)=120*100=12000

b) 24*25+24*37+24*38=24*(25+37+38)=24*100=2400

c) 53*(12+172-84)=53*100=5300

d) 8.25.2.4.5.125=(8*125)*(2*5)*(25*4)=1000000

`a,`

`2x^2 - 6x`

`= 2 (x^2 - 3x) `

`= 2 (x^2 - 2 . x . 3/2 + 9/4 - 9/4)`

`= 2 (x-3/2)^2 -9/2 >= 9/2`

Dấu "=" xảy ra khi :

`<=> (x-3/2)^2=0 <=> x-3/2=0 <=> x=3/2`

Vậy GTNN của BT là `9/2 <=> x=3/2`

`b,`

`x^2 + y^2 - x + 6y +10`

`= (x^2 - x)+(y^2 + 6y)+10`

`= (x^2 - 2 . x . 1/2 +1/4) + (y^2 + 2 . y . 3 + 9) +3/4`

`= (x-1/2)^2 + (y+3)^2 + 3/4 >= 3/4`

Dấu "=" xảy ra khi :

`<=> (x-1/2)^2=0, (y+3)^2=0`

`<=> x=1/2, y=-3`

Vậy GTNN của BT là `3/4 <=> x=1/2, y=-3`

làm giá trị lớn nhất nhá

`A =- |x+5| + 10`

Vì `-|x+5| =< 0`

`-> - |x+5|+10 =< 10`

`->A =< 10`

Dấu "`=`" xảy ra khi : `<=> |x+5|=0 <=> x=-5`

Vậy `max A=10 <=>x=-5`

\(\frac{4}{15}.\frac{5}{30}=\frac{20}{450}=\frac{2}{45}\)

\(4^{15}\times5^{30}\)

\(=\)\(\left(2^2\right)^{15}.5^{30}\)

\(=\)\(2^{30}.5^{30}\)

\(=\)\(\left(2.5\right)^{30}\)

\(=\)\(10^{30}\)