Q. If 4x2−12x=40, what are the possible values for x ?A) −2 and 5B) −5 and 2C) −5 and −8D) −5 and −16
Rewrite in Standard Form: Start by rewriting the given equation in standard quadratic form.The given equation is 4x2−12x=40. To rewrite it in standard form, we need to set the equation equal to zero.4x2−12x−40=0
Factor the Quadratic Equation: Factor the quadratic equation.To factor the equation, we look for two numbers that multiply to give −160(4×−40) and add to give −12 (the coefficient of x).The two numbers that satisfy these conditions are −20 and +8.So we can write the equation as:4x2−20x+8x−40=0Grouping the terms, we get:(4x2−20x)+(8x−40)=0Taking out the common factors, we have:4x(x−5)+8(x−5)=0Now we can factor out (x−5):(4×−40)0
Solve for x: Solve for x.We have the factored form (4x+8)(x−5)=0.Setting each factor equal to zero gives us the possible values for x:4x+8=0 or x−5=0Solving each equation for x gives us:4x=−8 or x=5x=−2 or x=5
Verify Solutions: Verify the solutions.We substitute x=−2 and x=5 back into the original equation to check if they are valid solutions.For x=−2:4(−2)2−12(−2)=4016+24=4040=40 (True)For x=5:4(5)2−12(5)=40100−60=4040=40 (True)Both solutions satisfy the original equation.
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