Question

solve by inspection. which two are solutions for $x^2 + 4x - 21 = 0$? (2 points)\\$\square$ $x = -3$\\$\square$ $x = 3$\\$\square$ $x = -7$\\$\square$ $x = 7$

Explanation:

Step1: Test \( x = -3 \)

Substitute \( x = -3 \) into \( x^2 + 4x - 21 \):
\( (-3)^2 + 4(-3) - 21 = 9 - 12 - 21 = -24
eq 0 \).

Step2: Test \( x = 3 \)

Substitute \( x = 3 \):
\( 3^2 + 4(3) - 21 = 9 + 12 - 21 = 0 \).

Step3: Test \( x = -7 \)

Substitute \( x = -7 \):
\( (-7)^2 + 4(-7) - 21 = 49 - 28 - 21 = 0 \).

Step4: Test \( x = 7 \)

Substitute \( x = 7 \):
\( 7^2 + 4(7) - 21 = 49 + 28 - 21 = 56
eq 0 \).

Answer:

B. \( x = 3 \), C. \( x = -7 \)