let f ( x ) = x ^ 2 + bx + c . if f ( 1 ) = 0 and f ( - 9 ) = 0 , then f ( x ) crosses the y - axis at what y - coordinate ?
"when x = 1 and when x = - 9 , the expression f ( x ) = x ² + bx + c equals 0 . then f ( x ) = ( x - 1 ) ( x + 9 ) f ( 0 ) = - 9 the answer is a ."
negate(divide(subtract(power(9, 2), 1), add(9, 1)))