Question

Bai1:tìm x biết. 

a)4×(x-5)-(x-1)×(4x-3)=5

b) (3x-4)×(x-2)=3x×(x-9)-3

c)(x-5)×(x-4)-(x+1)×(x-2)=7

d)(2x-1)×(x-2)-(x+3)×(2x-7)=3

Answer 1

a)4×(x-5)-(x-1)×(4x-3)=5

=>4x-20-4x²+7x-3-5=0

=>-4x²+11x-28=0

=>-4(x²-\(\frac{11x}{4}\)+7)=0

=>\(-4\left(x-\frac{11}{8}\right)^2-\frac{327}{16}< 0\)

=>vô nghiệm

 

Answer 2

b) (3x-4)(x-2)=3x(x-9)-3

=>3x²-10x+8=3x²-27x-3

=>17x=-11

=>x=-11/17

c)(x-5)×(x-4)-(x+1)×(x-2)=7

=>x²-9x+20-x²+x+2=7

=>22-8x=7

=>-8x=-15

=>x=8/15

 

Answer 3

d)(2x-1)×(x-2)-(x+3)×(2x-7)=3

=>2x²-5x+2-2x²+x+21=3

=>23-4x=3

=>-4x=-20

=>x=5