the answer would be y = 2x + 1
can u take a better pic :) so its more clear!!
Step-by-step explanation:
Answer:
D is the answer
Step-by-step explanation:
check your Unit Circle for the values of at 180°
![cos(\alpha - \beta)= cos(\alpha)cos(\beta) + sin(\alpha)sin(\beta) \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ cos(180-x)=-cos(x) \\\\[-0.35em] ~\dotfill\\\\ cos(180^o-x)\implies cos(180^o)cos(x)+sin(180^o)sin(x) \\\\\\ (-1)cos(x)+(0)sin(x)\implies -cos(x)](https://tex.z-dn.net/?f=cos%28%5Calpha%20-%20%5Cbeta%29%3D%20cos%28%5Calpha%29cos%28%5Cbeta%29%20%2B%20sin%28%5Calpha%29sin%28%5Cbeta%29%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20cos%28180-x%29%3D-cos%28x%29%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20cos%28180%5Eo-x%29%5Cimplies%20cos%28180%5Eo%29cos%28x%29%2Bsin%28180%5Eo%29sin%28x%29%20%5C%5C%5C%5C%5C%5C%20%28-1%29cos%28x%29%2B%280%29sin%28x%29%5Cimplies%20-cos%28x%29)
Ok
2x + y - z = 7
-2y +3z = -15
x + 2y - 5z = 17
combine 2nd 3rd
x - 2z = 2
x = 2z + 2
double first statement
4x + 2y - 2z = 14
combine with second statement
4x + z = -1
substitute 2z + 2 for x
8z + 8 + z = -1
combine like terms
9z + 8 = -1
sub 8 from both sides
9z = -9
divide both sides by 9
z = -1
substitute -1 for z in second statement
-2y - 3 = -15
add 3 to both sides
-2y = -12
divide both sides by -2
y = 6
substitute -1 for z into the fifth statement
x = -2 + 2
x = 0
