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Solve the system of equations.

[tex]
\begin{array}{l}
13x - y = 90 \\
y = x^2 - x - 42
\end{array}
[/tex]

Enter your answers in the boxes:
( [tex]\square[/tex] , [tex]\square[/tex] ) and ( [tex]\square[/tex] , [tex]\square[/tex] )


Sagot :

To solve the system of equations given, we need to find the values of [tex]\( x \)[/tex] and [tex]\( y \)[/tex] that satisfy both equations simultaneously. Here are the equations:

1. [tex]\( 13x - y = 90 \)[/tex]
2. [tex]\( y = x^2 - x - 42 \)[/tex]

Let's solve this system step by step:

### Step 1: Express [tex]\( y \)[/tex] from the first equation

From the first equation, we can express [tex]\( y \)[/tex] in terms of [tex]\( x \)[/tex]:

[tex]\[ 13x - y = 90 \implies y = 13x - 90 \][/tex]

### Step 2: Substitute [tex]\( y \)[/tex] into the second equation

Next, substitute this expression for [tex]\( y \)[/tex] into the second equation:

[tex]\[ y = x^2 - x - 42 \implies 13x - 90 = x^2 - x - 42 \][/tex]

### Step 3: Simplify the equation

Rearrange the equation to form a standard quadratic equation:

[tex]\[ 13x - 90 = x^2 - x - 42 \implies x^2 - x - 42 - 13x + 90 = 0 \implies x^2 - 14x + 48 = 0 \][/tex]

### Step 4: Solve the quadratic equation

We solve the quadratic equation [tex]\( x^2 - 14x + 48 = 0 \)[/tex]. This can be done by factoring:

[tex]\[ x^2 - 14x + 48 = (x - 6)(x - 8) = 0 \][/tex]

Thus, we have two potential solutions for [tex]\( x \)[/tex]:

[tex]\[ x = 6 \quad \text{or} \quad x = 8 \][/tex]

### Step 5: Find corresponding [tex]\( y \)[/tex] values

For [tex]\( x = 6 \)[/tex]:

[tex]\[ y = 13(6) - 90 = 78 - 90 = -12 \][/tex]

For [tex]\( x = 8 \)[/tex]:

[tex]\[ y = 13(8) - 90 = 104 - 90 = 14 \][/tex]

### Conclusion

The solutions to the system of equations are:

[tex]\[ (6, -12) \quad \text{and} \quad (8, 14) \][/tex]

So, the answers in the boxes should be:

(6, -12) and (8, 14)