Câu hỏi của ꔹꗴꔊꓧꗍꗴꔹ ꔹꗴꔊꓧꗍꗴꔹ

Question

BT: Tìm x
a) 2x.(x-3)-x(2x+1)-3.(x+5)=11
b) x.(x-1)-(x^2+3x-5)-2.(x+3)=7
c) 5x.(x-7)-(5x+1).x-(x+3).2=13
d) (2x^2-3x+5)-2x.(x-3)+(x-1).(-2)=10

Nguyễn Thị Diễm Quỳnh · Accepted Answer

a) $2x\left(x-3\right)-x\left(2x+1\right)-3\left(x+5\right)=11$

$\Rightarrow2x^2-6x-2x^2-x-3x-15=11$

$\Rightarrow-10x=26\Rightarrow x=-2,6$

Vậy ...........

b) $x\left(x-1\right)-\left(x^2+3x-5\right)-2\left(x+3\right)=17$

$\Rightarrow x^2-x-x^2-3x+5-2x-6=17$

$\Rightarrow-6x=18\Rightarrow x=-3$

c) $5x\left(x-7\right)-\left(5x+1\right)x-\left(x+3\right)2=13$

$\Rightarrow5x^2-35x-5x^2-x-2x-6=13$

$\Rightarrow-38x=19\Rightarrow x=-\frac{1}{2}$

d) $\left(2x^2-3x+5\right)-2x\left(x-3\right)+\left(x-1\right)\left(-2\right)=10$

$\Rightarrow2x^2-3x+5-2x^2+6x-2x+2=10$

$\Rightarrow x=3$Câu trả lời: a) $2x\left(x-3\right)-x\left(2x+1\right)-3\left(x+5\right)=11$