A student is solving the equation x2=13x This student has decided to divide both sides of
the equation by x and finds the solution x =13. The student checks the answer in the back
of the book and finds that x = 0 is also a solution. The student feels that this is a misprint.
How would you advise him or her?
A student is trying to solve the equation (x + 9)(x – 6) =6. The student has set x + 9 =6 and
x – 6 =6 and found that two solutions x = – 3, x =12. The student checks his or her results
by plugging in his or her solutions into the original equation and finds that they do not
work. How would you advise him or her?
Jason is given the following information: “The shortest side of a triangle is 4 cm less than
the middle side. The length of the longest side is 13 cm.” Jason claims that he can find the
lengths of the two shorter sides by solving the following equation:
x2+(x + 4)2=132
What is wrong with his reasoning?
Tom’s teacher asks him to solve the following problem: “The product of two consecutive
even numbers is 168. Find the numbers.” Tom rewords the problem and translates to the
following equation:
x(x + 1) = 168
Why is this equation not correct and what would the correct equation be?
In factoring a trinomial in y as (y+ a)(y+ b), what must be true of a and b, if the coefficient
of the last term of the trinomial is negative?
Mark’s teacher asked him to solve the following problem: “One leg of a right triangle is 7
m longer than the other. The length of the hypotenuse is 13 m. Find the lengths of the legs.”
Mark translated the problem into the following equation: (x2+ 7) +x2=132. Why is this
equation not correct and what would the correct equation be?