<span>x-y=11 2x+y=19
x=11+y
2(11+y)+y=19
22+2y+y=19
3y=-3
y=-1
x=11-1=10</span>
Answer:
Step-by-step explanation:
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Answer:
Option A
Step-by-step explanation:
Given expression:
<u>Option A</u>
⇒ (x - 4)(3x + 2)
⇒ (x × 3x) + (2 × x) + (-4 × 3x) + (-4 × 2)
⇒ (3x²) + (2x) + (-12x) + (-8)
⇒ 3x² + 2x - 12x - 8
⇒ 3x² - 10x - 8
3x² - 10x - 8 = 3x² - 10x - 8 (Yes!)
<u>Option B</u>
⇒ (3x - 4)(x - 2)
⇒ (3x × x) + (3x × -2) + (-4 × x) + (-4 × -2)
⇒ (3x²) + (-6x) + (-4x) + (8)
⇒ 3x² - 6x - 4x + (8)
⇒ 3x² - 10x + 8
3x² - 10x - 8 = 3x² - 10x + 8 (No!)
<u>Option C</u>
⇒ (3x - 4)(x + 2)
⇒ (3x × x) + (3x × 2) + (-4 × x) + (-4 × 2)
⇒ (3x²) + (6x) + (-4x) + (-8)
⇒ 3x² + 6x - 4x - 8
⇒ 3x² + 2x - 8
3x² - 10x - 8 = 3x² + 2x - 8 (No!)
<u>Option D</u>
⇒ (3x - 2)(x - 4)
⇒ (3x × x) + (3x × -4) + (-2 × x) + (-2 × -4)
⇒ (3x²) + (-12x) + (-2x) + (8)
⇒ 3x² - 12x - 2x + 8
⇒ 3x² - 14x + 8
3x² - 10x - 8 = 3x² - 14x + 8 (No!)
Since the expression of option A has the same value as the given expression, option A is correct.
(1) Repetition allowed : There are 4 choices for both positions, so 4 × 4 = 16 2-digit numbers can be formed. (2) Repetition not allowed : There are 4 options for tens position, and three options for ones position. Therefore, 4 × 3 = 12 2-digit numbers can be formed.
They all 3 have no solution!
