Question

Solve $\frac{3x^2+21x+4}{3x^2+27x+5}=\frac{x+7}{x+9}$

• A. $1$
• B. $6$
• C. $5$
• D. $4$

Answer 1

The correct option is A $1$

$\frac{3x^2+21x+4}{3x^2+27x+5}=\frac{x+7}{x+9}$
$=>\frac{3x(x+7)+4}{3x(x+9)+5}=\frac{x+7}{x+9}$
Let $(x+7)=a$ and $(x+9)=b$
$=>\frac{3x\left(a\right)+4}{3x\left(b\right)+5}=\frac{a}{b}$
$=>3xab+4b=3xab+5a$
$=>4(x+9)=5(x+7)$
$=>4x+36=5x+35$
$=>4x-5x=35-36$
$=>-x=-1$
$=>x=1$