To combine the functions \( b = 3r + 1 \) and \( y = 2b^2 \), we need to substitute the expression for \( b \) into the equation for \( y \).
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Start by substituting \( b \) in the equation for \( y \): \[ y = 2b^2 \] Substituting \( b = 3r + 1 \): \[ y = 2(3r + 1)^2 \]
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Now, we need to expand \( (3r + 1)^2 \): \[ (3r + 1)^2 = (3r)^2 + 2(3r)(1) + (1)^2 = 9r^2 + 6r + 1 \]
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Substitute this back into the \( y \) equation: \[ y = 2(9r^2 + 6r + 1) \]
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Distribute the 2: \[ y = 18r^2 + 12r + 2 \]
Now we have the combined equation: \[ y = 18r^2 + 12r + 2 \]
So, the final equation is: \[ y = 18r^2 + 12r + 2 \]