如题

NO.PZ2023010401000128 问题如下 In a simple economy with no foreign sector, the following equations applyIf the realinterest rate is 3% angovernment spenng increases to 2,000, the increase inaggregate income will closest to: A.1,000.00 B.1,163. C.7,143.00 Y = 4,200 + 0.86 × Y – 25 × r. Y = 30,000 – 178.6 × r. 3%, Y = 30,000 – 178.6× 3 = 29,464. Alternatively, Y – 0.86Y= 4,200 – 25 × r 0.14Y =4,200 – 256 × r.If governmentspenng increase1,000 to 2,000, then Y = 5,200 + 0.86 × Y – 25 × r. Y = 37,142 – 178.6 × r, whi3% woulY =37,142 – 178.6 × 3 = 36,607. Representing increase of 36,607 – 29,464 =7,143. Alternatively, 5,200, Y – 0.86Y = 5,200 – 25 ×r or 0.14 Y = 5,200 – 25 ×r. Or more simply, ∆G ÷ (1 – = 1,000/(1 – 0.86) =7,143. 请问下Y=C+I+G这个知识点具体在哪里？另外看不太懂解析，能否再详解一遍，谢谢

NO.PZ2023010401000128 问题如下 In a simple economy with no foreign sector, the following equations applyIf the realinterest rate is 3% angovernment spenng increases to 2,000, the increase inaggregate income will closest to: A.1,000.00 B.1,163. C.7,143.00 Y = 4,200 + 0.86 × Y – 25 × r. Y = 30,000 – 178.6 × r. 3%, Y = 30,000 – 178.6× 3 = 29,464. Alternatively, Y – 0.86Y= 4,200 – 25 × r 0.14Y =4,200 – 256 × r.If governmentspenng increase1,000 to 2,000, then Y = 5,200 + 0.86 × Y – 25 × r. Y = 37,142 – 178.6 × r, whi3% woulY =37,142 – 178.6 × 3 = 36,607. Representing increase of 36,607 – 29,464 =7,143. Alternatively, 5,200, Y – 0.86Y = 5,200 – 25 ×r or 0.14 Y = 5,200 – 25 ×r. Or more simply, ∆G ÷ (1 – = 1,000/(1 – 0.86) =7,143. 解题思路里面从联立方程得出0.14Y = 4,200 – 25 × r.，到增加政府支出1000变为Y = 5,200 – 25 × r.，这是不对的。因为0.14Y = 4,200 – 25 × r.这个公式是从Y=C+I+G三个函数合并项整理出来的。在Y=C+I+G这个线性方程中，在这个题里面G是与C和I的变化无关的独立常数=1000。那么现在常数增加1000，Y就是应该增加1000呀。