I wish I could swim

e) 0,6x(x – 0,5) – 0,3x(2x + 1,3) = 0,138   

⇒0,6x²-0,3-0,6x²-0,39x=0,138

⇒-0,3-0,39x=0,138

⇒-0,39x=0,138+0,3

⇒-0,39x=0,438

⇒x= \(\dfrac{0,438}{-0,39}\)

⇒x=\(\dfrac{-73}{65}\)

d) 5x(12x + 7) – 3x(20x – 5) = - 100

⇒60x²+35x-60x²+15=-100

⇒35x+15=-100

⇒35x=-100-15

⇒35x=-115

⇒x=\(\dfrac{-115}{35}\)

⇒x=\(\dfrac{-23}{7}\)

b) (3x – 3)(5 – 21x) + (7x + 4)(9x – 5) = 44

⇒15x-63x²-15+63x + 63x²-35x+36x-20=44

⇒79x-35=44

⇒79x=44+35

⇒79x=79

⇒x=1

a) 6x(5x + 3) + 3x(1 – 10x) = 7  

⇒ 30x²+18x+3x-30x²=7

⇒21x=7

⇒x=\(\dfrac{7}{21}\)

⇒x= \(\dfrac{1}{3}\)

cho mình xin câu hỏi ạ

16x\((\dfrac{-1}{4}x+\dfrac{4}{5}y)^2\)=16x\(\left(\dfrac{1}{16}x^2+\dfrac{-2}{5}xy+\dfrac{16}{25}y^2\right)=x^3-\dfrac{32}{5}x^2y+\dfrac{256}{25}xy^2\)

 2 .18 .14 + 3 .12.17- 4 .31. 9= 504 + 612 - 1116= 0

a) x(2x+1)-x²(x+2)+(x³-x+3)= 2x²+x-x³-2x²+x³-x+3= 3

b)x (3x²-x+5)-(2x³+3x-16)-x(x²-x+2)= 3x³-x²+5x-2x³-3x+16-x³+x²-2x= 16

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