Question

The product of two consecutive integer is $30$. Find the value of first integer.

• A. $5$ or $-6$
• B. $3$ or $-6$
• C. $5$ or $6$
• D. $-5$ or $-6$

Answer 1

The correct option is A $5$ or $-6$

Let the two consecutive numbers be $x$ and $x+1$]

Therefore, product of two consecutive number $=x(x+1)$

According to the given condition,

$x^2+x=30$

Simplify using the method of factorisation,

$x^2+6x-5x-30=0$

$x(x+6)-5(x-6)=0$

$(x+6)(x-5)=0$

Thus we get the value of $x=5$ or $-6$

So, the first number will be $5$ or $-6$.