Question

Need help can’t figure it out! Plz help thank you Y=x^2+2x Y=3x+20

Answer 1

A. y = x^2 + 2x          B. y= 3x +20        Substitute 3x +20 for y in Equation A.

A. (3x + 20) = x^2 + 2x                           Set equation A up equal to 0 by

  -3x -20              -3x -20                    subtracting 3x and 20 from both sides.

A. 0 = x^2 - x -20                                   Factor the quadratic equation and solve.

A. 0 = (x - 5)(x + 4)

A. x - 5= 0    x + 4= 0

      +5   +5      -4      -4

A. x = 5, x = -4                                       Now substitute the values for x back                                into the equations to find the values for y, and your solutions

y = (5)^2 + 2(5)          y = 3(5) +20         y = (-4)^2 + 2(-4)          y = 3(-4) +20

y= 25 +10                  y = 15 +20            y = 16 + (-8)                  y = -12 +20

y = 35                         y = 35                  y = 8                             y = 8

So your solutions are (5, 35) and (-4, 8).