Question

Which are the solutions to x^2+8x+7=0

Answer 1

Answer: x = -1, -7

Set the polynomial to standard form: ax² + bx + c (already given).

x² + 8x + 7 = 0

• a = 1
• b = 8
• c = 7

Factor the polynomial. To do this, find two numbers that multiply to get c and add together to get b. In this case, those two numbers are 1 and 7.

(x + 1)(x + 7) = 0

• 1 × 7 = 7
• 1 + 7 = 8

Set each factor equal to zero and solve for x. The factors in the equation are (x + 1) and (x + 7).

• (x + 1) = 0

x = -1

• (x + 7) = 0

x = -7

The solutions to x² + 8x + 7 are -1 and -7. You can check this by using FOIL.

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