Solve the equation if X = 3
3X2 – 21/3X =
A.
48
B.
20
C.
12
D.
6
The correct answer and Explanation is :
To solve the equation (3X^2 – \frac{21}{3}X) with (X = 3), let’s follow these steps:
- Substitute (X) into the equation: [
3(3)^2 – \frac{21}{3}(3)
] - Calculate (3(3)^2): [
(3)^2 = 9
] [
3 \times 9 = 27
] So, the first term becomes (27). - Calculate (\frac{21}{3}(3)): [
\frac{21}{3} = 7
] [
7 \times 3 = 21
] So, the second term becomes (21). - Subtract the second term from the first term: [
27 – 21 = 6
]
Thus, the value of the equation when (X = 3) is (6).
Explanation
To break this down further, the equation given is (3X^2 – \frac{21}{3}X). The goal is to evaluate this expression for a specific value of (X).
- First, handle the quadratic term: The term (3X^2) involves squaring (X), which in this case is 3. Squaring 3 gives us 9, and multiplying this by 3 results in 27.
- Next, deal with the linear term: The term (\frac{21}{3}X) simplifies to (7X). Substituting (X = 3) into (7X) results in (21).
- Finally, perform the subtraction: The expression is structured as a subtraction problem between the evaluated quadratic term (27) and the linear term (21). Thus, performing the subtraction yields (6).
By carefully following these steps, you can solve similar algebraic expressions by substituting values and simplifying each term. The result is a straightforward calculation showing that the answer to the given problem is (6).