Question

Elisa is $3$ years older than her brother Joseph. If the product of their ages is $10$. Find the age of Elisa.

• A. $3$ years
• B. $4$ years
• C. $5$ years
• D. $6$ years

Answer 1

Answer: (C)

$5$ years

Let $x$ be the age of brother Joseph.
$x+3=$ age of Elisa---(1)
So, product of their age $=x(x+3)=10$
$x^2+3x-10=0$
On factoring, we get,
$(x-2)(x+5)=0$
$x-2=0,x+5=0$
$x=2$ or $x=-5$
Substitute the value of $x=2$ in equation (1), we get
$x+3=$ age of Elisa
$2+3=5$
So, the age of Elisa is $5$ years