Q. y=−3x6y−7=23x2+x−5If (x1,y1) and (x2,y2) are the distinct solutions to the system of equations shown, what is the sum of the y1+y2 ?
Write Equations: Write down the given system of equations.We have the following system:y=−3x6y−7=23x2+x−5
Substitute y in Second Equation: Substitute the expression for y from the first equation into the second equation.Since y=−3x, we can replace y in the second equation with −3x:6(−3x−7)=2(3x2+x−5)
Eliminate Fraction: Multiply both sides of the equation by 6 to eliminate the fraction on the left side.6×(6−3x−7)=6×(23x2+x−5)This simplifies to:−3x−7=3×(3x2+x−5)
Multiply Out: Multiply out the right side of the equation. −3x−7=9x2+3x−15
Rearrange to Quadratic Equation: Rearrange the equation to set it to zero and form a quadratic equation.9x2+3x−15+3x+7=09x2+6x−8=0
Factor or Use Quadratic Formula: Factor the quadratic equation, if possible, or use the quadratic formula to find the roots.The quadratic equation 9x2+6x−8 does not factor easily, so we will use the quadratic formula:x=2a−b±b2−4acHere, a=9, b=6, and c=−8.
Calculate Discriminant: Calculate the discriminant b2−4ac to ensure that there are real solutions.Discriminant = b2−4ac = 62−4(9)(−8) = 36+288 = 324Since the discriminant is positive, there are two distinct real solutions.
Calculate Roots: Calculate the roots using the quadratic formula.x1,2=2⋅9−6±324x1,2=18−6±18x1=1812=32x2=18−24=−34
Find Corresponding y-values: Find the corresponding y-values using the first equation y=−3x.y(1)=−3×(32)=−2y(2)=−3×(−34)=4
Calculate Sum of y-values: Calculate the sum of y1+y2.y1+y2=−2+4=2
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