In Example 2, change the + before the 7x 2 to and then solve the equation.
Question:
In Example 2, change the + before the 7x2 to − and then solve the equation.
Data from Example 2
Solve the equation 2x4 + 7x2 = 4.
We first let y = x2 to write the equation in quadratic form. We will then solve the resulting quadratic equation for y. However, solutions for x are required, so we again let y = x2 to solve for x.
We can let y1 = 2x4 + 7x2 and y2 = 4 to solve the system on a calculator. The display is shown in Fig. 14.15, and we see that there are two points of intersection, one for x = 0.7071 (shown on screen) and the other for x = −0.7071 (not shown). Because 1/√2 = 0.7071, this verifies the real solutions. The imaginary solutions cannot be found graphically. Substitution of each value in the original equation shows each value to be a solution.
Step by Step Answer:
Basic Technical Mathematics
ISBN: 9780137529896
12th Edition
Authors: Allyn J. Washington, Richard Evans