GMAT-problem solving(數學-5)

Question

In the xy-plane, line k has positive slope and x-intercept 4.

If the area of the triangle formed by line k and the two axes is 12,

what is the y-intercept of line k ? Ans: (A)

(A) -6

(B) -4

(C) -3

(D) 3

(E) 6

詳解 謝謝

Answer 1

最佳解答

譯：

xy平面上，已知直線k與x軸交於4且斜率為正

(positive slope即斜率為正)

若直線k與二軸圍成的三角形面積是12

問直線k與y軸交於何處？

解：

設直線k的y截距為a

a×4÷2=12

→a=6

因斜率為正

∴直線k交y軸於-6＃