# Maths question help ASAP

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#1
Hello, this question is asking me to solve quadratics by completing the square. I understand how to complete the square however I don't understand what sort of an answer the question is looking for as it doesn't want the normal complete the square answer.

Show that if y = x2 + 8x - 3
then y ≥ -19 for all values of x

Thankyou!
0
6 years ago
#2
It is asking you to complete the square in order to find the vertex (minimum point of the curve), which should have a y-value of -19, and therefore because the curve is U shaped due to the positive coefficient of x^2, y will be greater or equal to -19 for all values of x. If you are unsure of how to obtain the vertex of a curve by completing the square, I could show you.
0
6 years ago
#3
If you complete the square then you will get a squared bracket that contains a term in x and then a constant outside the brackets. The minimum value of the squared bracket is 0 and any real number when squared becomes a positive number. So the minimum value or maximum value(if the x^2 term in the original equation is negative) of y (if the equation is in the form y=f(x) that is) is going the be the constant term outside of the brackets
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