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Answer:
a = - 2, [tex]\frac{9}{4}[/tex] , b = 2, - [tex]\frac{1}{8}[/tex]
Step-by-step explanation:
Since x = 1, y = 2 is a solution to the equations , then substitute these values into the 2 equations and solve for a and b
a + 2b = 2 → (1)
b + 2a² = 10 → (2)
In (1) subtract 2b from both sides
a = 2 - 2b → (3)
Substitute a = 2 - 2b into (2)
b + 2(2 - 2b)² = 10 ← expand parenthesis using FOIL
b + 2(4 - 8b + 4b²) = 10 ( simplify left side )
b + 8 - 16b + 8b² = 10 ( subtract 10 from both sides )
8b² - 15b - 2 = 0
Consider the factors of the product of the coefficient of the b² term and the constant term which sum to give the coefficient of the b- term
product = 8 × - 2 = - 16 and sum = - 15
The factors are - 16 and + 1
Use these factors to split the b- term
8b² - 16b + b - 2 = 0 ( factor first/second and third/fourth terms )
8b(b - 2) + 1(b - 2) = 0 ← factor out (b - 2) from each term
(b - 2)(8b + 1) = 0
Equate each factor to zero and solve for b
b - 2 = 0 ⇒ b = 2
8b + 1 = 0 ⇒ 8b = - 1 ⇒ b = - [tex]\frac{1}{8}[/tex]
Substitute these values into (3) and evaluate for a
b = 2 ⇒ a = 2 - 2(2) = 2 - 4 = - 2
b = - [tex]\frac{1}{8}[/tex] ⇒ a = 2 - 2(- [tex]\frac{1}{8}[/tex] ) = 2 + [tex]\frac{1}{4}[/tex] = 2 [tex]\frac{1}{4}[/tex] = [tex]\frac{9}{4}[/tex]