### Digital PSAT Math Section Sample

If [tex]\( 36 + 3(4x - 9) = c(2x + 1) + 25 \)[/tex] has no solution and [tex]\( c \)[/tex] is a constant, what is the value of [tex]\( c \)[/tex]?

A. [tex]\(-3\)[/tex]
B. [tex]\(3\)[/tex]
C. [tex]\(6\)[/tex]
D. [tex]\(12\)[/tex]



Answer :

To solve the problem [tex]\(36 + 3(4x - 9) = c(2x + 1) + 25\)[/tex] and determine the value of [tex]\(c\)[/tex] that makes the equation have no solution, we need to follow these steps:

1. Expand and simplify both sides of the equation.

[tex]\[ 36 + 3(4x - 9) = c(2x + 1) + 25 \][/tex]

2. Distribute the constants inside the parentheses.

[tex]\[ 36 + 3 \cdot 4x - 3 \cdot 9 = c \cdot 2x + c \cdot 1 + 25 \][/tex]
[tex]\[ 36 + 12x - 27 = 2cx + c + 25 \][/tex]

3. Combine like terms on the left side.

[tex]\[ 36 - 27 + 12x = 2cx + c + 25 \][/tex]
[tex]\[ 9 + 12x = 2cx + c + 25 \][/tex]

4. Rearrange terms to isolate the [tex]\(x\)[/tex] terms and constant terms on each side.

[tex]\[ 12x - 2cx = c + 25 - 9 \][/tex]
[tex]\[ 12x - 2cx = c + 16 \][/tex]

5. Factor out [tex]\(x\)[/tex] on the left-hand side.

[tex]\[ x(12 - 2c) = c + 16 \][/tex]

For the equation to have no solution, the coefficient of [tex]\(x\)[/tex] must be zero, and the constant terms must yield a contradiction (i.e., a non-zero value). This means:

[tex]\[ 12 - 2c = 0 \][/tex]

6. Solve for [tex]\(c\)[/tex].

[tex]\[ 12 - 2c = 0 \][/tex]
[tex]\[ 2c = 12 \][/tex]
[tex]\[ c = 6 \][/tex]

To confirm that this value of [tex]\(c\)[/tex] leads to a contradiction in the constant terms:

Substitute [tex]\(c = 6\)[/tex] back into the equation:

[tex]\[ x(12 - 2 \cdot 6) = 6 + 16 \][/tex]
[tex]\[ x(12 - 12) = 22 \][/tex]
[tex]\[ 0 = 22 \][/tex]

Since [tex]\(0 = 22\)[/tex] is a contradiction, the equation has no solution when [tex]\(c = 6\)[/tex].

Thus, the value of [tex]\(c\)[/tex] is [tex]\( \boxed{6} \)[/tex].