If $a^3 +3a^2 + 3a = 63,$ then the value of $a^2 +2a$ is :
Answer & explanation
Correct answer: option 3
Let's solve the given equation a3+3a2+3a=63 and find the value of a2+2a
We can factor the left side of the equation by recognizing it as a cube of a binomial:
(a+1)3=a3+3a2+3a+1
Comparing this with the given equation, we have:
(a+1)3=63+1
Taking the cube root of both sides, we get:
a + 1 = ∛(64)
Simplifying further, we have:
a + 1 = 4
Subtracting 1 from both sides:
a = 4 - 1
a = 3
Now we can find the value of $a^2 +2a$ = $3^2 +2×3$ = 15