`B=4x^2+5x-2`

`=4(x^2 +5/4x)-2`

`=4(x^2 +2. 5/8x+25/64-25/64)-2`

`=4(x+5/8)^2-25/16-2`

`=4(x+5/8)^2-57/16`

Do `4(x+5/8)^2>=0`

`=>4(x+5/8)^2-57/16>=-57/16`

Dấu `'='` xảy ra `<=>x+5/8=0`

`<=>x=-5/8`

Vậy Min `B=-57/16<=>x=-5/8`

`C=-2x^2+5x-1`

`=-2(x^2 -5/2x)-1`

`=-2(x^2-2.5/4x+25/16-25/16)-1`

`=-2(x-5/4)^2 +17/8`

Do `-2(x-5/4)^2<=0AAx`

`=>-2(x-5/4)^2+17/8<=17/8`

`<=>C<=17/8`

Dấu `'='` xảy ra `<=>x-5/4=0`

`<=>x=5/4`

Vậy `MaxC=17/8<=>x=5/4`

`(x+2)/2=3`

`<=>x+2=2.3=6`

`<=>x=6-2`

`<=>x=4`

Vậy`S={4}`

`2(x-1)+3(x-1)=0`

`=>(2+3)(x-1)=0`

`=>5(x-1)=0`

`=>x-1=0`

`=>x=1`

Vậy `x=1`

`M_(ASO_4)=10M_O`

`=>M_A +32+16xx4=10xx16`

`=>M_A=160-32-16xx4`

`=>M_A=64`

Vậy nguyên tử khối của `A` là `64đvC`

ảnh nèo cap coai 

ns z pa a cx khôq biếc :O

vip=)

`(25+x)/(49+x)=3/5`

`=>5(25+x)=3(49+x)`

`=>125+5x=147+3x`

`=>5x-3x=147-125`

`=>2x=22`

`=>x=22:2`

`=>x=11`

Vậy `x=11`

kcj nhé :]