Number n+1 is divisible by 3. Find out if number 4+7n is divisible by 3.

Answer 1

Yes! N+1 is divisible by 3 so N+1= 3* A (an integer)...that means that N= 3A-1.

4+7N therefore equals 4+7(3A-1) or 4 + 21A -7 or 21A - 3.

We can see that 3 factors out to give 3 (7a-1). Therefore, since 3 is a factor, the quantity is divisible by 3!

I love helping with SAT prep!

Blessings! Carla