Question 89760
y = x^2 – 7x – 2
:
The x intercepts occur when y = 0, therefore:
x^2 - 7x - 2 = 0
:
To the value of x, in this equation we have to us the quadratic formula:
:
In this equation a=1; b=-7; c=-2
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
:
{{{x = (-(-7) +- sqrt( -7^2 - 4 * 1 * -2 ))/(2*1) }}}
:
{{{x = (+7 +- sqrt( 49 - (-8) ))/(2) }}}; a minus a minus is a plus
:
{{{x = (+7 +- sqrt( 49 + 8 ))/(2) }}};
:
{{{x = (+7 +- sqrt( 57 ))/(2) }}};
:
Solution 1:
{{{x = (+7 +7.55)/(2) }}};
{{{x = 14.55/2}}};
x = +7.275
:
Solution 2:
{{{x = (+7 - 7.55)/(2) }}};
{{{x = -.55/(2) }}};
x = -.275
:
:
Check both solutions in the original equation