Question

Giúp mik với. Tính A)(10x+9)x-(5x-1)(2x+3); B)(⅓-y⁴)² C)(5x+y)².

Answer 1

a) Ta có: \(x\left(10x+9\right)-\left(5x-1\right)\left(2x+3\right)\)

\(=10x^2+9x-10x^2-15x+2x+3\)

\(=-4x+3\)

b) Ta có: \(\left(\dfrac{1}{3}-y^4\right)^2\)

\(=\left(\dfrac{1}{3}\right)^2-2\cdot\dfrac{1}{3}\cdot y^4+\left(y^4\right)^2\)

\(=y^8-\dfrac{2}{3}y^4+\dfrac{1}{9}\)

c) Ta có: \(\left(5x+y\right)^2\)

\(=\left(5x\right)^2+2\cdot5x\cdot y+y^2\)

\(=25x^2+10xy+y^2\)

Answer 2

a) (10x+9)x-(5x-1)(2x+3)

= 10x²+9x-10x²-15x+2x+3

= -4x+3

Answer 3

a)\(\left(10x+9\right)x-\left(5x-1\right)\left(2x+3\right)\)

\(=10x^2+9x-\left(10x^2+13x-3\right)\\ =-4x+3\)

b)\(\left(\dfrac{1}{3}-y\right)^2=\dfrac{1}{9}-\dfrac{2}{3}y^4+y^8\)

\(\left(5x+y\right)^2=25x^2-2.5xy+y^2\\ =25x^2-10xy+y^2\)

Answer 4

c) (5x+y)²

= 25x²+10xy+y²

Answer 5

b)\(\left(\dfrac{1}{3}-y^4\right)^2\)

= \(\dfrac{1}{9}-\dfrac{2}{3}y^4+y^8\)

Answer 6

a) (10x+9)x-(5x-1)(2x+3)

= 10x²+9x-10x²-15x+2x+3

= -4x+3

Answer 7

c) (5x+y)²

= 25x²+10xy+y²