Question

a. 100x^2 + 20x + 1 = 16

b. (x +5)^2 - (x+ 3)^2 = 7

Answer 1

a

\(\rightarrow\left(10x+1\right)^2=16\\ \rightarrow\left(10x+1\right)^2=4^2hoặc\left(10x+1\right)^2=\left(-4\right)^2\)

\(\rightarrow10x+1=4hoặc10x+1=-4\)

\(TH1:10x+1=4\\ 10x=3\\ x=\dfrac{3}{10}\)

\(TH2:10x+1=-4\\ 10x=-5\\ x=-\dfrac{1}{2}\)

vậy ...

b

\(\rightarrow x^2+10x+25-x^2-6x-9=7\\ \rightarrow4x+16=7\\ 4x=-9\\ x=-\dfrac{9}{4}\)

 

 

 

 

 

 

Answer 2

a: =>(10x+1)²=16

=>10x+1=4 hoặc 10x+1=-4

=>10x=3 hoặc 10x=-5

=>x=3/10 hoặc x=-1/2

b: \(\Leftrightarrow x^2+10x+25-x^2-6x-9=7\)

=>4x+16=7

=>4x=-9

hay x=-9/4