Write a \(+\) or a \(-\) sign in each box so the expressions on each side of the equal sign are equivalent.

1. \((x \; \boxed{\phantom{30}} \;18)(x \; \boxed{\phantom{30}} \; 3)=x^2-15x-54\)
2. \((x \; \boxed{\phantom{30}} \; 18)(x \; \boxed{\phantom{30}} \; 3)=x^2+21x+54\)
3. \((x \; \boxed{\phantom{30}} \; 18)(x \; \boxed{\phantom{30}} \; 3)=x^2+15x-54\)
4. \((x \; \boxed{\phantom{30}} \; 18)(x \; \boxed{\phantom{30}} \; 3)=x^2-21x+54\)

Match each quadratic expression in standard form with its equivalent expression in factored form.​​​​​​

Rewrite each expression in factored form. If you get stuck, try drawing a diagram.

1. \(x^2 -3x-28\)
2. \(x^2 +3x-28\)
3. \(x^2 +12x-28\)
4. \(x^2 -28x-60\)

Which equation has exactly one solution?

Elena solves the equation \(x^2=7x\) by dividing both sides by \(x\) to get \(x=7\). She says the solution is 7.

Lin solves the equation \(x^2=7x\) by rewriting the equation to get \(x^2-7x=0\). When she graphs the equation \(y=x^2-7x\), the \(x\)-intercepts are \((0,0)\) and \((7,0)\). She says the solutions are 0 and 7.

Do you agree with either of them? Explain or show how you know.