If the line y = 4x + c passes through (5, 11), what is its y-intercept?
Answer and explanation
Correct answer: -9
Because (5, 11) lies on y = 4x + c, substitute x = 5 and y = 11 into the equation: 11 = 4(5) + c = 20 + c. Subtracting 20 from both sides gives c = 11 - 20 = -9. In y = mx + c, c is the y-intercept, the value of y when x = 0. Therefore the y-intercept is -9, so option B is correct. Option A results from reversing the subtraction, while C and D use an incorrect operation or sign.
Frequently asked questions
What is the correct answer to this question?
-9
Why is this the correct answer?
Because (5, 11) lies on y = 4x + c, substitute x = 5 and y = 11 into the equation: 11 = 4(5) + c = 20 + c. Subtracting 20 from both sides gives c = 11 - 20 = -9. In y = mx + c, c is the y-intercept, the value of y when x = 0. Therefore the y-intercept is -9, so option B is correct. Option A results from reversing the subtraction, while C and D use an incorrect operation or sign.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Introduction to Polynomials. Topic: Slope and y-intercept.
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