Answer:
x= [tex]-2\pm \sqrt{11}[/tex]
Step-by-step explanation:
Here is the correct question: Using the quadratic formula to solve
x²+4x - 7. what are the values of x.
Solving by using quadratic formula.
Formula: [tex]\frac{-b\pm \sqrt{b^{2}-4(ac) } }{2a}[/tex]
∴ In the expression [tex]x^{2} +4x-7[/tex], we have a= 1, b= 4 and c= -7.
Now, subtituting the value in the formula.
=[tex]\frac{-4\pm \sqrt{4^{2}-4(1\times -7) } }{2\times 1}[/tex]
= [tex]\frac{-4\pm \sqrt{4^{2}-4(-7) } }{2}[/tex]
Opening parenthesis.
= [tex]\frac{-4\pm \sqrt{16+28 } }{2\times 1}[/tex]
= [tex]\frac{-4\pm \sqrt{44}}{2}[/tex]
We know 2²=4
= [tex]\frac{-4\pm \sqrt{2^{2}\times 11 }}{2}[/tex]
we know √a²=a
= [tex]\frac{-4\pm 2 \sqrt{11 }}{2}[/tex]
Taking 2 as common in the expression.
= [tex]\frac{2(-2\pm \sqrt{11}) }{2}[/tex]
Cancelling 2
= [tex]-2\pm \sqrt{11}[/tex]
Hence we get, [tex]x=-2\pm\sqrt{11}[/tex]
