Question

Solve. (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.)

Original question: Solve. (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.)

2xx+2x=49x+2\frac{2x}{x+2}-x=-\frac{49}{x+2}

x=7x=7

LEARN IT: SOLVE RATIONAL EQUATIONS BY MULTIPLYING BY THE LCD OF THE RATIONAL EXPR

Expert Verified Solution

thumb_up100%(1 rated)

Key takeaway: This is a rational equation with one denominator, so the fastest method is to multiply every term by the LCD and reduce it to a polynomial equation.

Step 1: Find the restriction

The denominator is x+2x+2, so

x2x\ne -2

Step 2: Multiply by the LCD

Multiply both sides by x+2x+2:

2xx+2(x+2)x(x+2)=49x+2(x+2)\frac{2x}{x+2}(x+2)-x(x+2)=\frac{-49}{x+2}(x+2)

This simplifies to

2xx(x+2)=492x-x(x+2)=-49

Step 3: Expand and solve

2xx22x=492x-x^2-2x=-49 x2=49-x^2=-49 x2=49x^2=49 x=±7x=\pm 7

Step 4: Check the restriction

Neither 77 nor 7-7 makes x+2=0x+2=0, so both are valid.

Answer: -7, 7


Pitfalls the pros know 👇 Do not forget the restriction x2x\ne -2. Also, when you solve x2=49x^2=49, remember that square roots give two answers: x=7x=7 and x=7x=-7.

What if the problem changes? If the right-hand side were different, the same LCD method would still work. The final step would depend on whether the reduced equation factors, becomes quadratic, or has no real solutions.

Tags: LCD, quadratic equation, restriction

FAQ

What are the solutions to this rational equation?

The solutions are x = -7 and x = 7. First multiply both sides by x + 2, then solve the resulting quadratic equation, and finally check that x = -2 is not used.

Why are there two answers?

Because the equation reduces to x^2 = 49, and a quadratic of this form has two square-root solutions: x = 7 and x = -7.

chat