Joyce is making mistake in first step.
What is quadratic equation?
The polynomial equation whose highest degree is two is called a quadratic equation.
The standard of quadratic equation is [tex]ax^{2} +bx + c = 0[/tex].
Quadratic formula for finding the value of x
x = (-b ± [tex]\sqrt{b^{2} -4ac}[/tex])/2a
According to the given question
we have
[tex]y = x^{2} -8x + 7[/tex]
here,
a = 1
b = -8 and c = 7
substitute the value of a, b and c in the quadratic formula
y = (8 ± [tex]\sqrt{8^{2} -4(1)(7)}[/tex])/2
y = (8 ±[tex]\sqrt{64 - 28}[/tex])/2
y = ( 8 ± [tex]\sqrt{36}[/tex])/2
y = (8 ± 6 )/2
y = [tex]\frac{8}{2}[/tex] ± [tex]\frac{6}{2}[/tex]
y = 4 ± 3
y = 4 + 3 and 4 -3
y = 7 and 1
In the first step Joyce making step instead of -8 Joyce had to write 8.
Hence, Joyce making mistake in the first step.
Learn more about quadratic equation:
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