Step-by-step explanation:
x² + y² = 153 and y = -4x.
=> x² + (-4x)² = 153
=> x² + 16x² = 153
=> 17x² = 153
=> x² = 9.
Answer:
x² = 9
x² + y² = 153 ----------------------(I)
y = -4x ----------------------(II)
Plugin y = -4x in equation (I)
x² + (-4x)² = 153
x² + 16x² = 153
17x² = 153
x² = 153/17
x = √9
x = 3
