Question

Solve for x: 3(x+6)=21. A)1 B) 5 C)9 D) 13 ​

Answer 1

Answer:

$\boxed {\boxed {\sf A. \ x=1}}$

Step-by-step explanation:

We are given the equation:

$3(x+6)=21$

We want to solve for x, so we must isolate the variable by performing inverse operations to both sides of the equation.

(x+6) is being multiplied by 3. The inverse of multiplication is division. Divide both sides of the equation by 3.

$\frac {3(x+6)}{3}=\frac{21}{3}$

$(x+6)=\frac{21}{3}$

$(x+6)=7$

Now 6 is being added to x. The inverse operation of addition is subtraction. Subtract 6 from both sides of the equation.

$x+6-6=7-6$

$x=7-6$

$x=1$

We can test our solution by plugging 1 in for x in the original equation.

$3(x+6)=21$

$3(1+6)=21$

$3(7)=21\\21=21$

This checks out (21 is equal to 21) so we know our answer is x=1.

Answer 2

Answer:

A. X=1

Step-by-step explanation:

To solve this problem, you have to use the distributive property.

Isolate the x from one side of an equation.

Distributive property:

$\sf{A(B+C)=AB+AC}$

First, divide by 3 from both sides of an equation.

$\dfrac{3(x+6)}{3}=\dfrac{21}{3}$

Solve.

21÷3=7

Rewrite the problem down.

x+6=7

Then, subtract by 6 from both sides.

$\sf{x+6-6=7-6}$

Solve.

7-6=1

$\Large\boxed{X=1}$

The solution is x=1, which is our answer.