Answer:
Step-by-step explanation:
y^2 + x^2 = 65
y + x = 7......x = 7 - y
y^2 + (7 - y)^2 = 65
y^2 + (7 - y)(7 - y) = 65
y^2 + 49 - 7y - 7y + y^2 = 65
2y^2 - 14y + 49 = 65
2y^2 - 14y + 49 - 65 = 0
2y^2 - 14y - 16 = 0
2(y^2 - 7y - 8) = 0
2(y + 1)(y - 8) = 0
y + 1 = 0 y - 8 = 0
y = -1 y = 8
solution :
y = -1...........y + x = 7.....-1 + x = 7......x = 7 + 1......x = 8........(8,-1)
y = 8........y + x = 7.....8 + x = 7......x = 7 - 8........x = -1........(-1,8)
I think it is the first and third one
A^2 - b^2 = (a - b)( a +b);
<span>cos^4x-sin^4x =( cos^2x + sin^2x )( cos^2x - sin^2x) = 1* cos2x = co2x.</span>
3/2 = 6
6/4= 6/40= 6 .999= ~ 7
